Merge branch 'master' into structured-attrs-shell

Conflicts: src/nix/develop.cc src/nix/get-env.sh tests/shell.nix
2024-11-10 08:16:15 +02:00 · 2021-07-12 15:46:41 +02:00 · 2021-07-12 15:46:41 +02:00 · 04cd2da84c
commit 04cd2da84c
parent 644415d391 9cf991f421
104 changed files with 1644 additions and 539 deletions
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@ -20,8 +20,7 @@ jobs:
        name: '${{ env.CACHIX_NAME }}'
        signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-    #- run: nix flake check
-    - run: nix-build -A checks.$(if [[ `uname` = Linux ]]; then echo x86_64-linux; else echo x86_64-darwin; fi)
+    - run: nix-build -A checks.$(nix-instantiate --eval -E '(builtins.currentSystem)')
  check_cachix:
    name: Cachix secret present for installer tests
    runs-on: ubuntu-latest
--- a/.gitignore
+++ b/.gitignore
@ -76,7 +76,6 @@ perl/Makefile.config
 # /tests/
 /tests/test-tmp
 /tests/common.sh
-/tests/dummy
 /tests/result*
 /tests/restricted-innocent
 /tests/shell
--- a/1
+++ b/1
@ -12,6 +12,7 @@ makefiles = \
  src/resolve-system-dependencies/local.mk \
  scripts/local.mk \
  misc/bash/local.mk \
+  misc/fish/local.mk \
  misc/zsh/local.mk \
  misc/systemd/local.mk \
  misc/launchd/local.mk \
--- a/Makefile.config.in
+++ b/Makefile.config.in
@ -1,3 +1,4 @@
+HOST_OS = @host_os@
 AR = @AR@
 BDW_GC_LIBS = @BDW_GC_LIBS@
 BOOST_LDFLAGS = @BOOST_LDFLAGS@
--- a/boehmgc-coroutine-sp-fallback.diff
+++ b/boehmgc-coroutine-sp-fallback.diff
@ -0,0 +1,42 @@
+diff --git a/pthread_stop_world.c b/pthread_stop_world.c
+index 1cee6a0b..46c3acd9 100644
+--- a/pthread_stop_world.c
+++ b/pthread_stop_world.c
+@@ -674,6 +674,8 @@ GC_INNER void GC_push_all_stacks(void)
+     struct GC_traced_stack_sect_s *traced_stack_sect;
+     pthread_t self = pthread_self();
+     word total_size = 0;
+    size_t stack_limit;
+    pthread_attr_t pattr;
+ 
+     if (!EXPECT(GC_thr_initialized, TRUE))
+       GC_thr_init();
+@@ -723,6 +725,28 @@ GC_INNER void GC_push_all_stacks(void)
+           hi = p->altstack + p->altstack_size;
+           /* FIXME: Need to scan the normal stack too, but how ? */
+           /* FIXME: Assume stack grows down */
+        } else {
+          if (pthread_getattr_np(p->id, &pattr)) {
+            ABORT("GC_push_all_stacks: pthread_getattr_np failed!");
+          }
+          if (pthread_attr_getstacksize(&pattr, &stack_limit)) {
+            ABORT("GC_push_all_stacks: pthread_attr_getstacksize failed!");
+          }
+          // When a thread goes into a coroutine, we lose its original sp until
+          // control flow returns to the thread.
+          // While in the coroutine, the sp points outside the thread stack,
+          // so we can detect this and push the entire thread stack instead,
+          // as an approximation.
+          // We assume that the coroutine has similarly added its entire stack.
+          // This could be made accurate by cooperating with the application
+          // via new functions and/or callbacks.
+          #ifndef STACK_GROWS_UP
+            if (lo >= hi || lo < hi - stack_limit) { // sp outside stack
+              lo = hi - stack_limit;
+            }
+          #else
+          #error "STACK_GROWS_UP not supported in boost_coroutine2 (as of june 2021), so we don't support it in Nix."
+          #endif
+         }
+         GC_push_all_stack_sections(lo, hi, traced_stack_sect);
+ #       ifdef STACK_GROWS_UP
--- a/configure.ac
+++ b/configure.ac
@ -231,7 +231,7 @@ AC_SUBST(HAVE_SECCOMP, [$have_seccomp])
 # Look for aws-cpp-sdk-s3.
 AC_LANG_PUSH(C++)
 AC_CHECK_HEADERS([aws/s3/S3Client.h],
-  [AC_DEFINE([ENABLE_S3], [1], [Whether to enable S3 support via aws-sdk-cpp.]) enable_s3=1], 
+  [AC_DEFINE([ENABLE_S3], [1], [Whether to enable S3 support via aws-sdk-cpp.]) enable_s3=1],
  [AC_DEFINE([ENABLE_S3], [0], [Whether to enable S3 support via aws-sdk-cpp.]) enable_s3=])
 AC_SUBST(ENABLE_S3, [$enable_s3])
 AC_LANG_POP(C++)
--- a/doc/manual/generate-builtins.nix
+++ b/doc/manual/generate-builtins.nix
@ -6,9 +6,11 @@ builtins:
 concatStrings (map
  (name:
    let builtin = builtins.${name}; in
-    "  - `builtins.${name}` " + concatStringsSep " " (map (s: "*${s}*") builtin.args)
-    + "  \n\n"
-    + concatStrings (map (s: "    ${s}\n") (splitLines builtin.doc)) + "\n\n"
+    "<dt><code>${name} "
+    + concatStringsSep " " (map (s: "<var>${s}</var>") builtin.args)
+    + "</code></dt>"
+    + "<dd>\n\n"
+    + builtin.doc
+    + "\n\n</dd>"
  )
  (attrNames builtins))
-
--- a/doc/manual/local.mk
+++ b/doc/manual/local.mk
@ -64,6 +64,7 @@ $(d)/conf-file.json: $(bindir)/nix
 $(d)/src/expressions/builtins.md: $(d)/builtins.json $(d)/generate-builtins.nix $(d)/src/expressions/builtins-prefix.md $(bindir)/nix
 	@cat doc/manual/src/expressions/builtins-prefix.md > $@.tmp
 	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtins.nix (builtins.fromJSON (builtins.readFile $<))' >> $@.tmp
+	@cat doc/manual/src/expressions/builtins-suffix.md >> $@.tmp
 	@mv $@.tmp $@

 $(d)/builtins.json: $(bindir)/nix
--- a/doc/manual/src/command-ref/env-common.md
+++ b/doc/manual/src/command-ref/env-common.md
@ -10,35 +10,39 @@ Most Nix commands interpret the following environment variables:
    A colon-separated list of directories used to look up Nix
    expressions enclosed in angle brackets (i.e., `<path>`). For
    instance, the value
-    
+
        /home/eelco/Dev:/etc/nixos
-    
+
    will cause Nix to look for paths relative to `/home/eelco/Dev` and
    `/etc/nixos`, in this order. It is also possible to match paths
    against a prefix. For example, the value
-    
+
        nixpkgs=/home/eelco/Dev/nixpkgs-branch:/etc/nixos
-    
+
    will cause Nix to search for `<nixpkgs/path>` in
    `/home/eelco/Dev/nixpkgs-branch/path` and `/etc/nixos/nixpkgs/path`.
-    
+
    If a path in the Nix search path starts with `http://` or
    `https://`, it is interpreted as the URL of a tarball that will be
    downloaded and unpacked to a temporary location. The tarball must
    consist of a single top-level directory. For example, setting
    `NIX_PATH` to
-    
-        nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-15.09.tar.gz
-    
-    tells Nix to download the latest revision in the Nixpkgs/NixOS 15.09
-    channel.
-    
-    A following shorthand can be used to refer to the official channels:
-    
-        nixpkgs=channel:nixos-15.09
-    
-    The search path can be extended using the `-I` option, which takes
-    precedence over `NIX_PATH`.
+
+        nixpkgs=https://github.com/NixOS/nixpkgs/archive/master.tar.gz
+
+    tells Nix to download and use the current contents of the
+    `master` branch in the `nixpkgs` repository.
+
+    The URLs of the tarballs from the official nixos.org channels (see
+    [the manual for `nix-channel`](nix-channel.md)) can be abbreviated
+    as `channel:<channel-name>`.  For instance, the following two
+    values of `NIX_PATH` are equivalent:
+
+        nixpkgs=channel:nixos-21.05
+        nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xz
+
+    The Nix search path can also be extended using the `-I` option to
+    many Nix commands, which takes precedence over `NIX_PATH`.

  - `NIX_IGNORE_SYMLINK_STORE`\
    Normally, the Nix store directory (typically `/nix/store`) is not
@ -50,7 +54,7 @@ Most Nix commands interpret the following environment variables:
    builds are deployed to machines where `/nix/store` resolves
    differently. If you are sure that you’re not going to do that, you
    can set `NIX_IGNORE_SYMLINK_STORE` to `1`.
-    
+
    Note that if you’re symlinking the Nix store so that you can put it
    on another file system than the root file system, on Linux you’re
    better off using `bind` mount points, e.g.,
@ -59,7 +63,7 @@ Most Nix commands interpret the following environment variables:
    $ mkdir /nix
    $ mount -o bind /mnt/otherdisk/nix /nix
    ```
-    
+
    Consult the mount 8 manual page for details.

  - `NIX_STORE_DIR`\
--- a/doc/manual/src/expressions/builtins-prefix.md
+++ b/doc/manual/src/expressions/builtins-prefix.md
@ -9,7 +9,8 @@ scope. Instead, you can access them through the `builtins` built-in
 value, which is a set that contains all built-in functions and values.
 For instance, `derivation` is also available as `builtins.derivation`.

-  - `derivation` *attrs*; `builtins.derivation` *attrs*\
-
-    `derivation` is described in [its own section](derivations.md).
-
+<dl>
+  <dt><code>derivation <var>attrs</var></code>;
+      <code>builtins.derivation <var>attrs</var></code></dt>
+  <dd><p><var>derivation</var> in described in
+         <a href="derivations.md">its own section</a>.</p></dd>
--- a/doc/manual/src/expressions/builtins-suffix.md
+++ b/doc/manual/src/expressions/builtins-suffix.md
@ -0,0 +1 @@
+</dl>
--- a/flake.lock
+++ b/flake.lock
@ -19,11 +19,11 @@
    },
    "nixpkgs": {
      "locked": {
-        "lastModified": 1622593737,
-        "narHash": "sha256-9loxFJg85AbzJrSkU4pE/divZ1+zOxDy2FSjlrufCB8=",
+        "lastModified": 1624862269,
+        "narHash": "sha256-JFcsh2+7QtfKdJFoPibLFPLgIW6Ycnv8Bts9a7RYme0=",
        "owner": "NixOS",
        "repo": "nixpkgs",
-        "rev": "bb8a5e54845012ed1375ffd5f317d2fdf434b20e",
+        "rev": "f77036342e2b690c61c97202bf48f2ce13acc022",
        "type": "github"
      },
      "original": {
--- a/flake.nix
+++ b/flake.nix
@ -20,6 +20,8 @@
      linuxSystems = linux64BitSystems ++ [ "i686-linux" ];
      systems = linuxSystems ++ [ "x86_64-darwin" "aarch64-darwin" ];

+      crossSystems = [ "armv6l-linux" "armv7l-linux" ];
+
      forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f system);

      # Memoize nixpkgs for different platforms for efficiency.
@ -79,7 +81,7 @@
            buildPackages.mercurial
            buildPackages.jq
          ]
-          ++ lib.optionals stdenv.isLinux [(pkgs.util-linuxMinimal or pkgs.utillinuxMinimal)];
+          ++ lib.optionals stdenv.hostPlatform.isLinux [(buildPackages.util-linuxMinimal or buildPackages.utillinuxMinimal)];

        buildDeps =
          [ curl
@ -93,7 +95,7 @@
          ]
          ++ lib.optionals stdenv.isLinux [libseccomp]
          ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium
-          ++ lib.optional stdenv.isx86_64 libcpuid;
+          ++ lib.optional stdenv.hostPlatform.isx86_64 libcpuid;

        awsDeps = lib.optional (stdenv.isLinux || stdenv.isDarwin)
          (aws-sdk-cpp.override {
@ -102,7 +104,13 @@
          });

        propagatedDeps =
-          [ (boehmgc.override { enableLargeConfig = true; })
+          [ ((boehmgc.override {
+              enableLargeConfig = true;
+            }).overrideAttrs(o: {
+              patches = (o.patches or []) ++ [
+                ./boehmgc-coroutine-sp-fallback.diff
+              ];
+            }))
          ];

        perlDeps =
@ -133,10 +141,11 @@

            substitute ${./scripts/install.in} $out/install \
              ${pkgs.lib.concatMapStrings
-                (system:
-                  '' \
-                  --replace '@tarballHash_${system}@' $(nix --experimental-features nix-command hash-file --base16 --type sha256 ${self.hydraJobs.binaryTarball.${system}}/*.tar.xz) \
-                  --replace '@tarballPath_${system}@' $(tarballPath ${self.hydraJobs.binaryTarball.${system}}/*.tar.xz) \
+                (system: let
+                    tarball = if builtins.elem system crossSystems then self.hydraJobs.binaryTarballCross.x86_64-linux.${system} else self.hydraJobs.binaryTarball.${system};
+                  in '' \
+                  --replace '@tarballHash_${system}@' $(nix --experimental-features nix-command hash-file --base16 --type sha256 ${tarball}/*.tar.xz) \
+                  --replace '@tarballPath_${system}@' $(tarballPath ${tarball}/*.tar.xz) \
                  ''
                )
                systems
@ -174,6 +183,77 @@

      };

+      binaryTarball = buildPackages: nix: pkgs: let
+        inherit (pkgs) cacert;
+        installerClosureInfo = buildPackages.closureInfo { rootPaths = [ nix cacert ]; };
+      in
+
+      buildPackages.runCommand "nix-binary-tarball-${version}"
+        { #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
+          meta.description = "Distribution-independent Nix bootstrap binaries for ${pkgs.system}";
+        }
+        ''
+          cp ${installerClosureInfo}/registration $TMPDIR/reginfo
+          cp ${./scripts/create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
+          substitute ${./scripts/install-nix-from-closure.sh} $TMPDIR/install \
+            --subst-var-by nix ${nix} \
+            --subst-var-by cacert ${cacert}
+
+          substitute ${./scripts/install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
+            --subst-var-by nix ${nix} \
+            --subst-var-by cacert ${cacert}
+          substitute ${./scripts/install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
+            --subst-var-by nix ${nix} \
+            --subst-var-by cacert ${cacert}
+          substitute ${./scripts/install-multi-user.sh} $TMPDIR/install-multi-user \
+            --subst-var-by nix ${nix} \
+            --subst-var-by cacert ${cacert}
+
+          if type -p shellcheck; then
+            # SC1090: Don't worry about not being able to find
+            #         $nix/etc/profile.d/nix.sh
+            shellcheck --exclude SC1090 $TMPDIR/install
+            shellcheck $TMPDIR/create-darwin-volume.sh
+            shellcheck $TMPDIR/install-darwin-multi-user.sh
+            shellcheck $TMPDIR/install-systemd-multi-user.sh
+
+            # SC1091: Don't panic about not being able to source
+            #         /etc/profile
+            # SC2002: Ignore "useless cat" "error", when loading
+            #         .reginfo, as the cat is a much cleaner
+            #         implementation, even though it is "useless"
+            # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
+            #         root's home directory
+            shellcheck --external-sources \
+              --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
+          fi
+
+          chmod +x $TMPDIR/install
+          chmod +x $TMPDIR/create-darwin-volume.sh
+          chmod +x $TMPDIR/install-darwin-multi-user.sh
+          chmod +x $TMPDIR/install-systemd-multi-user.sh
+          chmod +x $TMPDIR/install-multi-user
+          dir=nix-${version}-${pkgs.system}
+          fn=$out/$dir.tar.xz
+          mkdir -p $out/nix-support
+          echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
+          tar cvfJ $fn \
+            --owner=0 --group=0 --mode=u+rw,uga+r \
+            --absolute-names \
+            --hard-dereference \
+            --transform "s,$TMPDIR/install,$dir/install," \
+            --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
+            --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
+            --transform "s,$NIX_STORE,$dir/store,S" \
+            $TMPDIR/install \
+            $TMPDIR/create-darwin-volume.sh \
+            $TMPDIR/install-darwin-multi-user.sh \
+            $TMPDIR/install-systemd-multi-user.sh \
+            $TMPDIR/install-multi-user \
+            $TMPDIR/reginfo \
+            $(cat ${installerClosureInfo}/store-paths)
+        '';
+
    in {

      # A Nixpkgs overlay that overrides the 'nix' and
@ -285,7 +365,7 @@

          outputs = [ "out" "bin" "dev" ];

-          nativeBuildInputs = [ which ];
+          nativeBuildInputs = [ buildPackages.which ];

          configurePhase = ''
              ${if (stdenv.isDarwin && stdenv.isAarch64) then "echo \"HAVE_SANDBOX_INIT=false\" > configure.local" else ""}
@ -304,92 +384,33 @@

        buildStatic = nixpkgs.lib.genAttrs linux64BitSystems (system: self.packages.${system}.nix-static);

+        buildCross = nixpkgs.lib.genAttrs crossSystems (crossSystem:
+          nixpkgs.lib.genAttrs ["x86_64-linux"] (system: self.packages.${system}."nix-${crossSystem}"));
+
        # Perl bindings for various platforms.
        perlBindings = nixpkgs.lib.genAttrs systems (system: self.packages.${system}.nix.perl-bindings);

        # Binary tarball for various platforms, containing a Nix store
        # with the closure of 'nix' package, and the second half of
        # the installation script.
-        binaryTarball = nixpkgs.lib.genAttrs systems (system:
+        binaryTarball = nixpkgs.lib.genAttrs systems (system: binaryTarball nixpkgsFor.${system} nixpkgsFor.${system}.nix nixpkgsFor.${system});

-          with nixpkgsFor.${system};
-
-          let
-            installerClosureInfo = closureInfo { rootPaths = [ nix cacert ]; };
-          in
-
-          runCommand "nix-binary-tarball-${version}"
-            { #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
-              meta.description = "Distribution-independent Nix bootstrap binaries for ${system}";
-            }
-            ''
-              cp ${installerClosureInfo}/registration $TMPDIR/reginfo
-              cp ${./scripts/create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
-              substitute ${./scripts/install-nix-from-closure.sh} $TMPDIR/install \
-                --subst-var-by nix ${nix} \
-                --subst-var-by cacert ${cacert}
-
-              substitute ${./scripts/install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
-                --subst-var-by nix ${nix} \
-                --subst-var-by cacert ${cacert}
-              substitute ${./scripts/install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
-                --subst-var-by nix ${nix} \
-                --subst-var-by cacert ${cacert}
-              substitute ${./scripts/install-multi-user.sh} $TMPDIR/install-multi-user \
-                --subst-var-by nix ${nix} \
-                --subst-var-by cacert ${cacert}
-
-              if type -p shellcheck; then
-                # SC1090: Don't worry about not being able to find
-                #         $nix/etc/profile.d/nix.sh
-                shellcheck --exclude SC1090 $TMPDIR/install
-                shellcheck $TMPDIR/create-darwin-volume.sh
-                shellcheck $TMPDIR/install-darwin-multi-user.sh
-                shellcheck $TMPDIR/install-systemd-multi-user.sh
-
-                # SC1091: Don't panic about not being able to source
-                #         /etc/profile
-                # SC2002: Ignore "useless cat" "error", when loading
-                #         .reginfo, as the cat is a much cleaner
-                #         implementation, even though it is "useless"
-                # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
-                #         root's home directory
-                shellcheck --external-sources \
-                  --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
-              fi
-
-              chmod +x $TMPDIR/install
-              chmod +x $TMPDIR/create-darwin-volume.sh
-              chmod +x $TMPDIR/install-darwin-multi-user.sh
-              chmod +x $TMPDIR/install-systemd-multi-user.sh
-              chmod +x $TMPDIR/install-multi-user
-              dir=nix-${version}-${system}
-              fn=$out/$dir.tar.xz
-              mkdir -p $out/nix-support
-              echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
-              tar cvfJ $fn \
-                --owner=0 --group=0 --mode=u+rw,uga+r \
-                --absolute-names \
-                --hard-dereference \
-                --transform "s,$TMPDIR/install,$dir/install," \
-                --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
-                --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
-                --transform "s,$NIX_STORE,$dir/store,S" \
-                $TMPDIR/install \
-                $TMPDIR/create-darwin-volume.sh \
-                $TMPDIR/install-darwin-multi-user.sh \
-                $TMPDIR/install-systemd-multi-user.sh \
-                $TMPDIR/install-multi-user \
-                $TMPDIR/reginfo \
-                $(cat ${installerClosureInfo}/store-paths)
-            '');
+        binaryTarballCross = nixpkgs.lib.genAttrs ["x86_64-linux"] (system: builtins.listToAttrs (map (crossSystem: {
+          name = crossSystem;
+          value = let
+            nixpkgsCross = import nixpkgs {
+              inherit system crossSystem;
+              overlays = [ self.overlay ];
+            };
+          in binaryTarball nixpkgsFor.${system} self.packages.${system}."nix-${crossSystem}" nixpkgsCross;
+        }) crossSystems));

        # The first half of the installation script. This is uploaded
        # to https://nixos.org/nix/install. It downloads the binary
        # tarball for the user's system and calls the second half of the
        # installation script.
-        installerScript = installScriptFor [ "x86_64-linux" "i686-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
-        installerScriptForGHA = installScriptFor [ "x86_64-linux" "x86_64-darwin" ];
+        installerScript = installScriptFor [ "x86_64-linux" "i686-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" "armv6l-linux" "armv7l-linux" ];
+        installerScriptForGHA = installScriptFor [ "x86_64-linux" "x86_64-darwin" "armv6l-linux" "armv7l-linux"];

        # Line coverage analysis.
        coverage =
@ -483,11 +504,14 @@
            # `NIX_DAEMON_SOCKET_PATH` which is required for the tests to work
            # againstLatestStable = testNixVersions pkgs pkgs.nix pkgs.nixStable;
          } "touch $out";
-      });
+      } // (if system == "x86_64-linux" then (builtins.listToAttrs (map (crossSystem: {
+        name = "binaryTarball-${crossSystem}";
+        value = self.hydraJobs.binaryTarballCross.${system}.${crossSystem};
+      }) crossSystems)) else {}));

      packages = forAllSystems (system: {
        inherit (nixpkgsFor.${system}) nix;
-      } // nixpkgs.lib.optionalAttrs (builtins.elem system linux64BitSystems) {
+      } // (nixpkgs.lib.optionalAttrs (builtins.elem system linux64BitSystems) {
        nix-static = let
          nixpkgs = nixpkgsFor.${system}.pkgsStatic;
        in with commonDeps nixpkgs; nixpkgs.stdenv.mkDerivation {
@ -525,8 +549,49 @@
          stripAllList = ["bin"];

          strictDeps = true;
+
+          hardeningDisable = [ "pie" ];
        };
-      });
+      } // builtins.listToAttrs (map (crossSystem: {
+        name = "nix-${crossSystem}";
+        value = let
+          nixpkgsCross = import nixpkgs {
+            inherit system crossSystem;
+            overlays = [ self.overlay ];
+          };
+        in with commonDeps nixpkgsCross; nixpkgsCross.stdenv.mkDerivation {
+          name = "nix-${version}";
+
+          src = self;
+
+          VERSION_SUFFIX = versionSuffix;
+
+          outputs = [ "out" "dev" "doc" ];
+
+          nativeBuildInputs = nativeBuildDeps;
+          buildInputs = buildDeps ++ propagatedDeps;
+
+          configureFlags = [ "--sysconfdir=/etc" "--disable-doc-gen" ];
+
+          enableParallelBuilding = true;
+
+          makeFlags = "profiledir=$(out)/etc/profile.d";
+
+          doCheck = true;
+
+          installFlags = "sysconfdir=$(out)/etc";
+
+          postInstall = ''
+            mkdir -p $doc/nix-support
+            echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
+            mkdir -p $out/nix-support
+            echo "file binary-dist $out/bin/nix" >> $out/nix-support/hydra-build-products
+          '';
+
+          doInstallCheck = true;
+          installCheckFlags = "sysconfdir=$(out)/etc";
+        };
+      }) crossSystems)));

      defaultPackage = forAllSystems (system: self.packages.${system}.nix);

--- a/maintainers/upload-release.pl
+++ b/maintainers/upload-release.pl
@ -110,6 +110,9 @@ downloadFile("binaryTarball.i686-linux", "1");
 downloadFile("binaryTarball.x86_64-linux", "1");
 downloadFile("binaryTarball.aarch64-linux", "1");
 downloadFile("binaryTarball.x86_64-darwin", "1");
+downloadFile("binaryTarball.aarch64-darwin", "1");
+downloadFile("binaryTarballCross.x86_64-linux.armv6l-linux", "1");
+downloadFile("binaryTarballCross.x86_64-linux.armv7l-linux", "1");
 downloadFile("installerScript", "1");

 for my $fn (glob "$tmpDir/*") {
@ -153,6 +156,7 @@ write_file("$nixpkgsDir/nixos/modules/installer/tools/nix-fallback-paths.nix",
           "  i686-linux = \"" . getStorePath("build.i686-linux") . "\";\n" .
           "  aarch64-linux = \"" . getStorePath("build.aarch64-linux") . "\";\n" .
           "  x86_64-darwin = \"" . getStorePath("build.x86_64-darwin") . "\";\n" .
+           "  aarch64-darwin = \"" . getStorePath("build.aarch64-darwin") . "\";\n" .
           "}\n");

 system("cd $nixpkgsDir && git commit -a -m 'nix-fallback-paths.nix: Update to $version'") == 0 or die;
--- a/misc/fish/completion.fish
+++ b/misc/fish/completion.fish
@ -0,0 +1,37 @@
+function _nix_complete
+  # Get the current command up to a cursor.
+  # - Behaves correctly even with pipes and nested in commands like env.
+  # - TODO: Returns the command verbatim (does not interpolate variables).
+  #   That might not be optimal for arguments like -f.
+  set -l nix_args (commandline --current-process --tokenize --cut-at-cursor)
+  # --cut-at-cursor with --tokenize removes the current token so we need to add it separately.
+  # https://github.com/fish-shell/fish-shell/issues/7375
+  # Can be an empty string.
+  set -l current_token (commandline --current-token --cut-at-cursor)
+
+  # Nix wants the index of the argv item to complete but the $nix_args variable
+  # also contains the program name (argv[0]) so we would need to subtract 1.
+  # But the variable also misses the current token so it cancels out.
+  set -l nix_arg_to_complete (count $nix_args)
+
+  env NIX_GET_COMPLETIONS=$nix_arg_to_complete $nix_args $current_token
+end
+
+function _nix_accepts_files
+  set -l response (_nix_complete)
+  # First line is either filenames or no-filenames.
+  test $response[1] = 'filenames'
+end
+
+function _nix
+  set -l response (_nix_complete)
+  # Skip the first line since it handled by _nix_accepts_files.
+  # Tail lines each contain a command followed by a tab character and, optionally, a description.
+  # This is also the format fish expects.
+  string collect -- $response[2..-1]
+end
+
+# Disable file path completion if paths do not belong in the current context.
+complete --command nix --condition 'not _nix_accepts_files' --no-files
+
+complete --command nix --arguments '(_nix)'
--- a/misc/fish/local.mk
+++ b/misc/fish/local.mk
@ -0,0 +1 @@
+$(eval $(call install-file-as, $(d)/completion.fish, $(datarootdir)/fish/vendor_completions.d/nix.fish, 0644))
--- a/misc/launchd/local.mk
+++ b/misc/launchd/local.mk
@ -1,4 +1,4 @@
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN

  $(eval $(call install-data-in, $(d)/org.nixos.nix-daemon.plist, $(prefix)/Library/LaunchDaemons))

--- a/misc/systemd/local.mk
+++ b/misc/systemd/local.mk
@ -1,4 +1,4 @@
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX

  $(foreach n, nix-daemon.socket nix-daemon.service, $(eval $(call install-file-in, $(d)/$(n), $(prefix)/lib/systemd/system, 0644)))

--- a/misc/upstart/local.mk
+++ b/misc/upstart/local.mk
@ -1,4 +1,4 @@
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX

  $(foreach n, nix-daemon.conf, $(eval $(call install-file-in, $(d)/$(n), $(sysconfdir)/init, 0644)))

--- a/misc/zsh/completion.zsh
+++ b/misc/zsh/completion.zsh
@ -1,3 +1,5 @@
+#compdef nix
+
 function _nix() {
  local ifs_bk="$IFS"
  local input=("${(Q)words[@]}")
@ -18,4 +20,4 @@ function _nix() {
  _describe 'nix' suggestions
 }

-compdef _nix nix
+_nix "$@"
--- a/mk/lib.mk
+++ b/mk/lib.mk
@ -10,8 +10,25 @@ bin-scripts :=
 noinst-scripts :=
 man-pages :=
 install-tests :=
-OS = $(shell uname -s)

+ifdef HOST_OS
+  HOST_KERNEL = $(firstword $(subst -, ,$(HOST_OS)))
+  ifeq ($(HOST_KERNEL), cygwin)
+    HOST_CYGWIN = 1
+  endif
+  ifeq ($(patsubst darwin%,,$(HOST_KERNEL)),)
+    HOST_DARWIN = 1
+  endif
+  ifeq ($(patsubst freebsd%,,$(HOST_KERNEL)),)
+    HOST_FREEBSD = 1
+  endif
+  ifeq ($(HOST_KERNEL), linux)
+    HOST_LINUX = 1
+  endif
+  ifeq ($(patsubst solaris%,,$(HOST_KERNEL)),)
+    HOST_SOLARIS = 1
+  endif
+endif

 # Hack to define a literal space.
 space :=
@ -50,16 +67,16 @@ endif
 BUILD_SHARED_LIBS ?= 1

 ifeq ($(BUILD_SHARED_LIBS), 1)
-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
    GLOBAL_CFLAGS += -U__STRICT_ANSI__ -D_GNU_SOURCE
    GLOBAL_CXXFLAGS += -U__STRICT_ANSI__ -D_GNU_SOURCE
  else
    GLOBAL_CFLAGS += -fPIC
    GLOBAL_CXXFLAGS += -fPIC
  endif
-  ifneq ($(OS), Darwin)
-   ifneq ($(OS), SunOS)
-    ifneq ($(OS), FreeBSD)
+  ifndef HOST_DARWIN
+   ifndef HOST_SOLARIS
+    ifndef HOST_FREEBSD
     GLOBAL_LDFLAGS += -Wl,--no-copy-dt-needed-entries
    endif
   endif
--- a/mk/libraries.mk
+++ b/mk/libraries.mk
@ -1,9 +1,9 @@
 libs-list :=

-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
  SO_EXT = dylib
 else
-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
    SO_EXT = dll
  else
    SO_EXT = so
@ -59,7 +59,7 @@ define build-library
  $(1)_OBJS := $$(addprefix $(buildprefix), $$(addsuffix .o, $$(basename $$(_srcs))))
  _libs := $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_PATH))

-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
    $(1)_INSTALL_DIR ?= $$(bindir)
  else
    $(1)_INSTALL_DIR ?= $$(libdir)
@ -73,18 +73,18 @@ define build-library
  ifeq ($(BUILD_SHARED_LIBS), 1)

    ifdef $(1)_ALLOW_UNDEFINED
-      ifeq ($(OS), Darwin)
+      ifdef HOST_DARWIN
        $(1)_LDFLAGS += -undefined suppress -flat_namespace
      endif
    else
-      ifneq ($(OS), Darwin)
-        ifneq (CYGWIN,$(findstring CYGWIN,$(OS)))
+      ifndef HOST_DARWIN
+        ifndef HOST_CYGWIN
          $(1)_LDFLAGS += -Wl,-z,defs
        endif
      endif
    endif

-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
      $(1)_LDFLAGS += -Wl,-soname=$$($(1)_NAME).$(SO_EXT)
    endif

@ -93,7 +93,7 @@ define build-library
    $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
 	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED)

-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
      $(1)_LDFLAGS_USE += -Wl,-rpath,$$(abspath $$(_d))
    endif
    $(1)_LDFLAGS_USE += -L$$(_d) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
@ -108,7 +108,7 @@ define build-library
 	$$(trace-ld) $(CXX) -o $$@ -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))

    $(1)_LDFLAGS_USE_INSTALLED += -L$$(DESTDIR)$$($(1)_INSTALL_DIR) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
      ifeq ($(SET_RPATH_TO_LIBS), 1)
        $(1)_LDFLAGS_USE_INSTALLED += -Wl,-rpath,$$($(1)_INSTALL_DIR)
      else
--- a/nix-rust/local.mk
+++ b/nix-rust/local.mk
@ -11,12 +11,12 @@ libnixrust_INSTALL_PATH := $(libdir)/libnixrust.$(SO_EXT)
 libnixrust_LDFLAGS_USE := -L$(d)/target/$(RUST_DIR) -lnixrust
 libnixrust_LDFLAGS_USE_INSTALLED := -L$(libdir) -lnixrust

-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
 libnixrust_LDFLAGS_USE += -ldl
 libnixrust_LDFLAGS_USE_INSTALLED += -ldl
 endif

-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
 libnixrust_BUILD_FLAGS = NIX_LDFLAGS="-undefined dynamic_lookup"
 else
 libnixrust_LDFLAGS_USE += -Wl,-rpath,$(abspath $(d)/target/$(RUST_DIR))
@ -31,7 +31,7 @@ $(libnixrust_PATH): $(call rwildcard, $(d)/src, *.rs) $(d)/Cargo.toml

 $(libnixrust_INSTALL_PATH): $(libnixrust_PATH)
 	$(target-gen) cp $^ $@
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
 	install_name_tool -id $@ $@
 endif

@ -40,7 +40,7 @@ clean: clean-rust
 clean-rust:
 	$(suppress) rm -rfv nix-rust/target

-ifneq ($(OS), Darwin)
+ifndef HOST_DARWIN
 check: rust-tests

 rust-tests:
--- a/perl/Makefile.config.in
+++ b/perl/Makefile.config.in
@ -1,3 +1,4 @@
+HOST_OS = @host_os@
 CC = @CC@
 CFLAGS = @CFLAGS@
 CXX = @CXX@
--- a/perl/configure.ac
+++ b/perl/configure.ac
@ -7,6 +7,8 @@ CXXFLAGS=
 AC_PROG_CC
 AC_PROG_CXX

+AC_CANONICAL_HOST
+
 # Use 64-bit file system calls so that we can support files > 2 GiB.
 AC_SYS_LARGEFILE

--- a/perl/local.mk
+++ b/perl/local.mk
@ -28,7 +28,7 @@ Store_CXXFLAGS = \

 Store_LDFLAGS := $(SODIUM_LIBS) $(NIX_LIBS)

-ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+ifdef HOST_CYGWIN
  archlib = $(shell perl -E 'use Config; print $$Config{archlib};')
  libperl = $(shell perl -E 'use Config; print $$Config{libperl};')
  Store_LDFLAGS += $(shell find ${archlib} -name ${libperl})
--- a/scripts/install.in
+++ b/scripts/install.in
@ -40,13 +40,23 @@ case "$(uname -s).$(uname -m)" in
        path=@tarballPath_aarch64-linux@
        system=aarch64-linux
        ;;
+    Linux.armv6l_linux)
+        hash=@tarballHash_armv6l-linux@
+        path=@tarballPath_armv6l-linux@
+        system=armv6l-linux
+        ;;
+    Linux.armv7l_linux)
+        hash=@tarballHash_armv7l-linux@
+        path=@tarballPath_armv7l-linux@
+        system=armv7l-linux
+        ;;
    Darwin.x86_64)
        hash=@tarballHash_x86_64-darwin@
        path=@tarballPath_x86_64-darwin@
        system=x86_64-darwin
        ;;
    Darwin.arm64|Darwin.aarch64)
-        hash=@binaryTarball_aarch64-darwin@
+        hash=@tarballHash_aarch64-darwin@
        path=@tarballPath_aarch64-darwin@
        system=aarch64-darwin
        ;;
--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@ -277,7 +277,16 @@ connected:

        auto drv = store->readDerivation(*drvPath);
        auto outputHashes = staticOutputHashes(*store, drv);
-        drv.inputSrcs = store->parseStorePathSet(inputs);
+
+        // Hijack the inputs paths of the derivation to include all the paths
+        // that come from the `inputDrvs` set.
+        // We don’t do that for the derivations whose `inputDrvs` is empty
+        // because
+        // 1. It’s not needed
+        // 2. Changing the `inputSrcs` set changes the associated output ids,
+        //  which break CA derivations
+        if (!drv.inputDrvs.empty())
+            drv.inputSrcs = store->parseStorePathSet(inputs);

        auto result = sshStore->buildDerivation(*drvPath, drv);

--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@ -188,7 +188,7 @@ void MixProfile::updateProfile(const BuiltPaths & buildables)
    }

    if (result.size() != 1)
-        throw Error("'--profile' requires that the arguments produce a single store path, but there are %d", result.size());
+        throw UsageError("'--profile' requires that the arguments produce a single store path, but there are %d", result.size());

    updateProfile(result[0]);
 }
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@ -171,14 +171,50 @@ Strings SourceExprCommand::getDefaultFlakeAttrPathPrefixes()

 void SourceExprCommand::completeInstallable(std::string_view prefix)
 {
-    if (file) return; // FIXME
+    if (file) {
+        evalSettings.pureEval = false;
+        auto state = getEvalState();
+        Expr *e = state->parseExprFromFile(
+            resolveExprPath(state->checkSourcePath(lookupFileArg(*state, *file)))
+        );

-    completeFlakeRefWithFragment(
-        getEvalState(),
-        lockFlags,
-        getDefaultFlakeAttrPathPrefixes(),
-        getDefaultFlakeAttrPaths(),
-        prefix);
+        Value root;
+        state->eval(e, root);
+
+        auto autoArgs = getAutoArgs(*state);
+
+        std::string prefix_ = std::string(prefix);
+        auto sep = prefix_.rfind('.');
+        std::string searchWord;
+        if (sep != std::string::npos) {
+            searchWord = prefix_.substr(sep, std::string::npos);
+            prefix_ = prefix_.substr(0, sep);
+        } else {
+            searchWord = prefix_;
+            prefix_ = "";
+        }
+
+        Value &v1(*findAlongAttrPath(*state, prefix_, *autoArgs, root).first);
+        state->forceValue(v1);
+        Value v2;
+        state->autoCallFunction(*autoArgs, v1, v2);
+
+        if (v2.type() == nAttrs) {
+            for (auto & i : *v2.attrs) {
+                std::string name = i.name;
+                if (name.find(searchWord) == 0) {
+                    completions->add(i.name);
+                }
+            }
+        }
+    } else {
+        completeFlakeRefWithFragment(
+            getEvalState(),
+            lockFlags,
+            getDefaultFlakeAttrPathPrefixes(),
+            getDefaultFlakeAttrPaths(),
+            prefix);
+    }
 }

 void completeFlakeRefWithFragment(
@ -573,10 +609,10 @@ InstallableFlake::getCursors(EvalState & state)

 std::shared_ptr<flake::LockedFlake> InstallableFlake::getLockedFlake() const
 {
+    flake::LockFlags lockFlagsApplyConfig = lockFlags;
+    lockFlagsApplyConfig.applyNixConfig = true;
    if (!_lockedFlake) {
-        _lockedFlake = std::make_shared<flake::LockedFlake>(lockFlake(*state, flakeRef, lockFlags));
-        _lockedFlake->flake.config.apply();
-        // FIXME: send new config to the daemon.
+        _lockedFlake = std::make_shared<flake::LockedFlake>(lockFlake(*state, flakeRef, lockFlagsApplyConfig));
    }
    return _lockedFlake;
 }
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@ -19,7 +19,7 @@ static Strings parseAttrPath(std::string_view s)
            ++i;
            while (1) {
                if (i == s.end())
-                    throw Error("missing closing quote in selection path '%1%'", s);
+                    throw ParseError("missing closing quote in selection path '%1%'", s);
                if (*i == '"') break;
                cur.push_back(*i++);
            }
@ -116,14 +116,14 @@ Pos findDerivationFilename(EvalState & state, Value & v, std::string what)

    auto colon = pos.rfind(':');
    if (colon == std::string::npos)
-        throw Error("cannot parse meta.position attribute '%s'", pos);
+        throw ParseError("cannot parse meta.position attribute '%s'", pos);

    std::string filename(pos, 0, colon);
    unsigned int lineno;
    try {
        lineno = std::stoi(std::string(pos, colon + 1));
    } catch (std::invalid_argument & e) {
-        throw Error("cannot parse line number '%s'", pos);
+        throw ParseError("cannot parse line number '%s'", pos);
    }

    Symbol file = state.symbols.create(filename);
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@ -64,7 +64,11 @@ static char * dupStringWithLen(const char * s, size_t size)

 RootValue allocRootValue(Value * v)
 {
+#if HAVE_BOEHMGC
    return std::allocate_shared<Value *>(traceable_allocator<Value *>(), v);
+#else
+    return std::make_shared<Value *>(v);
+#endif
 }


@ -233,22 +237,34 @@ static void * oomHandler(size_t requested)
 }

 class BoehmGCStackAllocator : public StackAllocator {
-  boost::coroutines2::protected_fixedsize_stack stack {
-    // We allocate 8 MB, the default max stack size on NixOS.
-    // A smaller stack might be quicker to allocate but reduces the stack
-    // depth available for source filter expressions etc.
-    std::max(boost::context::stack_traits::default_size(), static_cast<std::size_t>(8 * 1024 * 1024))
+    boost::coroutines2::protected_fixedsize_stack stack {
+        // We allocate 8 MB, the default max stack size on NixOS.
+        // A smaller stack might be quicker to allocate but reduces the stack
+        // depth available for source filter expressions etc.
+        std::max(boost::context::stack_traits::default_size(), static_cast<std::size_t>(8 * 1024 * 1024))
    };

+    // This is specific to boost::coroutines2::protected_fixedsize_stack.
+    // The stack protection page is included in sctx.size, so we have to
+    // subtract one page size from the stack size.
+    std::size_t pfss_usable_stack_size(boost::context::stack_context &sctx) {
+        return sctx.size - boost::context::stack_traits::page_size();
+    }
+
  public:
    boost::context::stack_context allocate() override {
        auto sctx = stack.allocate();
-        GC_add_roots(static_cast<char *>(sctx.sp) - sctx.size, sctx.sp);
+
+        // Stacks generally start at a high address and grow to lower addresses.
+        // Architectures that do the opposite are rare; in fact so rare that
+        // boost_routine does not implement it.
+        // So we subtract the stack size.
+        GC_add_roots(static_cast<char *>(sctx.sp) - pfss_usable_stack_size(sctx), sctx.sp);
        return sctx;
    }

    void deallocate(boost::context::stack_context sctx) override {
-        GC_remove_roots(static_cast<char *>(sctx.sp) - sctx.size, sctx.sp);
+        GC_remove_roots(static_cast<char *>(sctx.sp) - pfss_usable_stack_size(sctx), sctx.sp);
        stack.deallocate(sctx);
    }

@ -908,7 +924,7 @@ void EvalState::evalFile(const Path & path_, Value & v, bool mustBeTrivial)
        // computation.
        if (mustBeTrivial &&
            !(dynamic_cast<ExprAttrs *>(e)))
-            throw Error("file '%s' must be an attribute set", path);
+            throw EvalError("file '%s' must be an attribute set", path);
        eval(e, v);
    } catch (Error & e) {
        addErrorTrace(e, "while evaluating the file '%1%':", path2);
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@ -298,6 +298,11 @@ LockedFlake lockFlake(

    auto flake = getFlake(state, topRef, lockFlags.useRegistries, flakeCache);

+    if (lockFlags.applyNixConfig) {
+        flake.config.apply();
+        // FIXME: send new config to the daemon.
+    }
+
    try {

        // FIXME: symlink attack
@ -359,7 +364,12 @@ LockedFlake lockFlake(
                       ancestors? */
                    auto i = overrides.find(inputPath);
                    bool hasOverride = i != overrides.end();
-                    if (hasOverride) overridesUsed.insert(inputPath);
+                    if (hasOverride) {
+                        overridesUsed.insert(inputPath);
+                        // Respect the “flakeness” of the input even if we
+                        // override it
+                        i->second.isFlake = input2.isFlake;
+                    }
                    auto & input = hasOverride ? i->second : input2;

                    /* Resolve 'follows' later (since it may refer to an input
--- a/src/libexpr/flake/flake.hh
+++ b/src/libexpr/flake/flake.hh
@ -104,6 +104,10 @@ struct LockFlags
       references like 'nixpkgs'. */
    bool useRegistries = true;

+    /* Whether to apply flake's nixConfig attribute to the configuration */
+
+    bool applyNixConfig = false;
+
    /* Whether mutable flake references (i.e. those without a Git
       revision or similar) without a corresponding lock are
       allowed. Mutable flake references with a lock are always
--- a/src/libexpr/local.mk
+++ b/src/libexpr/local.mk
@ -16,7 +16,7 @@ libexpr_CXXFLAGS += -I src/libutil -I src/libstore -I src/libfetchers -I src/lib
 libexpr_LIBS = libutil libstore libfetchers

 libexpr_LDFLAGS = -lboost_context
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
 libexpr_LDFLAGS += -ldl
 endif

--- a/src/libexpr/primops/fetchMercurial.cc
+++ b/src/libexpr/primops/fetchMercurial.cc
@ -62,6 +62,7 @@ static void prim_fetchMercurial(EvalState & state, const Pos & pos, Value * * ar
    fetchers::Attrs attrs;
    attrs.insert_or_assign("type", "hg");
    attrs.insert_or_assign("url", url.find("://") != std::string::npos ? url : "file://" + url);
+    attrs.insert_or_assign("name", name);
    if (ref) attrs.insert_or_assign("ref", *ref);
    if (rev) attrs.insert_or_assign("rev", rev->gitRev());
    auto input = fetchers::Input::fromAttrs(std::move(attrs));
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@ -7,6 +7,7 @@

 #include <ctime>
 #include <iomanip>
+#include <regex>

 namespace nix {

@ -60,10 +61,19 @@ void emitTreeAttrs(
    v.attrs->sort();
 }

-std::string fixURI(std::string uri, EvalState &state)
+std::string fixURI(std::string uri, EvalState &state, const std::string & defaultScheme = "file")
 {
    state.checkURI(uri);
-    return uri.find("://") != std::string::npos ? uri : "file://" + uri;
+    return uri.find("://") != std::string::npos ? uri : defaultScheme + "://" + uri;
+}
+
+std::string fixURIForGit(std::string uri, EvalState & state)
+{
+    static std::regex scp_uri("([^/].*)@(.*):(.*)");
+    if (uri[0] != '/' && std::regex_match(uri, scp_uri))
+        return fixURI(std::regex_replace(uri, scp_uri, "$1@$2/$3"), state, "ssh");
+    else
+        return fixURI(uri, state);
 }

 void addURI(EvalState &state, fetchers::Attrs &attrs, Symbol name, std::string v)
@ -72,13 +82,18 @@ void addURI(EvalState &state, fetchers::Attrs &attrs, Symbol name, std::string v
    attrs.emplace(name, n == "url" ? fixURI(v, state) : v);
 }

+struct FetchTreeParams {
+    bool emptyRevFallback = false;
+    bool allowNameArgument = false;
+};
+
 static void fetchTree(
    EvalState &state,
    const Pos &pos,
    Value **args,
    Value &v,
    const std::optional<std::string> type,
-    bool emptyRevFallback = false
+    const FetchTreeParams & params = FetchTreeParams{}
 ) {
    fetchers::Input input;
    PathSet context;
@ -119,17 +134,25 @@ static void fetchTree(
                .errPos = pos
            });

+        if (!params.allowNameArgument)
+            if (auto nameIter = attrs.find("name"); nameIter != attrs.end())
+                throw Error({
+                    .msg = hintfmt("attribute 'name' isn’t supported in call to 'fetchTree'"),
+                    .errPos = pos
+                });
+
+
        input = fetchers::Input::fromAttrs(std::move(attrs));
    } else {
-        auto url = fixURI(state.coerceToString(pos, *args[0], context, false, false), state);
+        auto url = state.coerceToString(pos, *args[0], context, false, false);

        if (type == "git") {
            fetchers::Attrs attrs;
            attrs.emplace("type", "git");
-            attrs.emplace("url", url);
+            attrs.emplace("url", fixURIForGit(url, state));
            input = fetchers::Input::fromAttrs(std::move(attrs));
        } else {
-            input = fetchers::Input::fromURL(url);
+            input = fetchers::Input::fromURL(fixURI(url, state));
        }
    }

@ -144,13 +167,13 @@ static void fetchTree(
    if (state.allowedPaths)
        state.allowedPaths->insert(tree.actualPath);

-    emitTreeAttrs(state, tree, input2, v, emptyRevFallback);
+    emitTreeAttrs(state, tree, input2, v, params.emptyRevFallback);
 }

 static void prim_fetchTree(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
    settings.requireExperimentalFeature("flakes");
-    fetchTree(state, pos, args, v, std::nullopt);
+    fetchTree(state, pos, args, v, std::nullopt, FetchTreeParams { .allowNameArgument = false });
 }

 // FIXME: document
@ -292,7 +315,7 @@ static RegisterPrimOp primop_fetchTarball({

 static void prim_fetchGit(EvalState &state, const Pos &pos, Value **args, Value &v)
 {
-    fetchTree(state, pos, args, v, "git", true);
+    fetchTree(state, pos, args, v, "git", FetchTreeParams { .emptyRevFallback = true, .allowNameArgument = true });
 }

 static RegisterPrimOp primop_fetchGit({
--- a/src/libfetchers/fetchers.cc
+++ b/src/libfetchers/fetchers.cc
@ -200,12 +200,17 @@ void Input::markChangedFile(
    return scheme->markChangedFile(*this, file, commitMsg);
 }

+std::string Input::getName() const
+{
+    return maybeGetStrAttr(attrs, "name").value_or("source");
+}
+
 StorePath Input::computeStorePath(Store & store) const
 {
    auto narHash = getNarHash();
    if (!narHash)
        throw Error("cannot compute store path for mutable input '%s'", to_string());
-    return store.makeFixedOutputPath(FileIngestionMethod::Recursive, *narHash, "source");
+    return store.makeFixedOutputPath(FileIngestionMethod::Recursive, *narHash, getName());
 }

 std::string Input::getType() const
--- a/src/libfetchers/fetchers.hh
+++ b/src/libfetchers/fetchers.hh
@ -81,6 +81,8 @@ public:
        std::string_view file,
        std::optional<std::string> commitMsg) const;

+    std::string getName() const;
+
    StorePath computeStorePath(Store & store) const;

    // Convenience functions for common attributes.
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@ -60,7 +60,7 @@ struct GitInputScheme : InputScheme
        if (maybeGetStrAttr(attrs, "type") != "git") return {};

        for (auto & [name, value] : attrs)
-            if (name != "type" && name != "url" && name != "ref" && name != "rev" && name != "shallow" && name != "submodules" && name != "lastModified" && name != "revCount" && name != "narHash" && name != "allRefs")
+            if (name != "type" && name != "url" && name != "ref" && name != "rev" && name != "shallow" && name != "submodules" && name != "lastModified" && name != "revCount" && name != "narHash" && name != "allRefs" && name != "name")
                throw Error("unsupported Git input attribute '%s'", name);

        parseURL(getStrAttr(attrs, "url"));
@ -167,10 +167,10 @@ struct GitInputScheme : InputScheme

    std::pair<Tree, Input> fetch(ref<Store> store, const Input & _input) override
    {
-        auto name = "source";
-
        Input input(_input);

+        std::string name = input.getName();
+
        bool shallow = maybeGetBoolAttr(input.attrs, "shallow").value_or(false);
        bool submodules = maybeGetBoolAttr(input.attrs, "submodules").value_or(false);
        bool allRefs = maybeGetBoolAttr(input.attrs, "allRefs").value_or(false);
@ -270,7 +270,7 @@ struct GitInputScheme : InputScheme
                    return files.count(file);
                };

-                auto storePath = store->addToStore("source", actualUrl, FileIngestionMethod::Recursive, htSHA256, filter);
+                auto storePath = store->addToStore(input.getName(), actualUrl, FileIngestionMethod::Recursive, htSHA256, filter);

                // FIXME: maybe we should use the timestamp of the last
                // modified dirty file?
--- a/src/libfetchers/github.cc
+++ b/src/libfetchers/github.cc
@ -207,7 +207,7 @@ struct GitArchiveInputScheme : InputScheme

        auto url = getDownloadUrl(input);

-        auto [tree, lastModified] = downloadTarball(store, url.url, "source", true, url.headers);
+        auto [tree, lastModified] = downloadTarball(store, url.url, input.getName(), true, url.headers);

        input.attrs.insert_or_assign("lastModified", uint64_t(lastModified));

--- a/src/libfetchers/mercurial.cc
+++ b/src/libfetchers/mercurial.cc
@ -74,7 +74,7 @@ struct MercurialInputScheme : InputScheme
        if (maybeGetStrAttr(attrs, "type") != "hg") return {};

        for (auto & [name, value] : attrs)
-            if (name != "type" && name != "url" && name != "ref" && name != "rev" && name != "revCount" && name != "narHash")
+            if (name != "type" && name != "url" && name != "ref" && name != "rev" && name != "revCount" && name != "narHash" && name != "name")
                throw Error("unsupported Mercurial input attribute '%s'", name);

        parseURL(getStrAttr(attrs, "url"));
@ -147,10 +147,10 @@ struct MercurialInputScheme : InputScheme

    std::pair<Tree, Input> fetch(ref<Store> store, const Input & _input) override
    {
-        auto name = "source";
-
        Input input(_input);

+        auto name = input.getName();
+
        auto [isLocal, actualUrl_] = getActualUrl(input);
        auto actualUrl = actualUrl_; // work around clang bug

@ -193,7 +193,7 @@ struct MercurialInputScheme : InputScheme
                    return files.count(file);
                };

-                auto storePath = store->addToStore("source", actualUrl, FileIngestionMethod::Recursive, htSHA256, filter);
+                auto storePath = store->addToStore(input.getName(), actualUrl, FileIngestionMethod::Recursive, htSHA256, filter);

                return {
                    Tree(store->toRealPath(storePath), std::move(storePath)),
--- a/src/libfetchers/registry.cc
+++ b/src/libfetchers/registry.cc
@ -124,6 +124,13 @@ std::shared_ptr<Registry> getUserRegistry()
    return userRegistry;
 }

+std::shared_ptr<Registry> getCustomRegistry(const Path & p)
+{
+    static auto customRegistry =
+        Registry::read(p, Registry::Custom);
+    return customRegistry;
+}
+
 static std::shared_ptr<Registry> flagRegistry =
    std::make_shared<Registry>(Registry::Flag);

--- a/src/libfetchers/registry.hh
+++ b/src/libfetchers/registry.hh
@ -14,6 +14,7 @@ struct Registry
        User = 1,
        System = 2,
        Global = 3,
+        Custom = 4,
    };

    RegistryType type;
@ -48,6 +49,8 @@ typedef std::vector<std::shared_ptr<Registry>> Registries;

 std::shared_ptr<Registry> getUserRegistry();

+std::shared_ptr<Registry> getCustomRegistry(const Path & p);
+
 Path getUserRegistryPath();

 Registries getRegistries(ref<Store> store);
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@ -196,7 +196,7 @@ struct TarballInputScheme : InputScheme
        if (maybeGetStrAttr(attrs, "type") != "tarball") return {};

        for (auto & [name, value] : attrs)
-            if (name != "type" && name != "url" && /* name != "hash" && */ name != "narHash")
+            if (name != "type" && name != "url" && /* name != "hash" && */ name != "narHash" && name != "name")
                throw Error("unsupported tarball input attribute '%s'", name);

        Input input;
@ -226,7 +226,7 @@ struct TarballInputScheme : InputScheme

    std::pair<Tree, Input> fetch(ref<Store> store, const Input & input) override
    {
-        auto tree = downloadTarball(store, getStrAttr(input.attrs, "url"), "source", false).first;
+        auto tree = downloadTarball(store, getStrAttr(input.attrs, "url"), input.getName(), false).first;
        return {std::move(tree), input};
    }
 };
--- a/src/libmain/progress-bar.cc
+++ b/src/libmain/progress-bar.cc
@ -484,7 +484,7 @@ Logger * makeProgressBar(bool printBuildLogs)
 {
    return new ProgressBar(
        printBuildLogs,
-        isatty(STDERR_FILENO) && getEnv("TERM").value_or("dumb") != "dumb"
+        shouldANSI()
    );
 }

--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@ -738,6 +738,63 @@ void DerivationGoal::cleanupPostOutputsRegisteredModeNonCheck()
 {
 }

+void runPostBuildHook(
+    Store & store,
+    Logger & logger,
+    const StorePath & drvPath,
+    StorePathSet outputPaths
+)
+{
+    auto hook = settings.postBuildHook;
+    if (hook == "")
+        return;
+
+    Activity act(logger, lvlInfo, actPostBuildHook,
+            fmt("running post-build-hook '%s'", settings.postBuildHook),
+            Logger::Fields{store.printStorePath(drvPath)});
+    PushActivity pact(act.id);
+    std::map<std::string, std::string> hookEnvironment = getEnv();
+
+    hookEnvironment.emplace("DRV_PATH", store.printStorePath(drvPath));
+    hookEnvironment.emplace("OUT_PATHS", chomp(concatStringsSep(" ", store.printStorePathSet(outputPaths))));
+
+    RunOptions opts(settings.postBuildHook, {});
+    opts.environment = hookEnvironment;
+
+    struct LogSink : Sink {
+        Activity & act;
+        std::string currentLine;
+
+        LogSink(Activity & act) : act(act) { }
+
+        void operator() (std::string_view data) override {
+            for (auto c : data) {
+                if (c == '\n') {
+                    flushLine();
+                } else {
+                    currentLine += c;
+                }
+            }
+        }
+
+        void flushLine() {
+            act.result(resPostBuildLogLine, currentLine);
+            currentLine.clear();
+        }
+
+        ~LogSink() {
+            if (currentLine != "") {
+                currentLine += '\n';
+                flushLine();
+            }
+        }
+    };
+    LogSink sink(act);
+
+    opts.standardOut = &sink;
+    opts.mergeStderrToStdout = true;
+    runProgram2(opts);
+}

 void DerivationGoal::buildDone()
 {
@ -803,57 +860,15 @@ void DerivationGoal::buildDone()
           being valid. */
        registerOutputs();

-        if (settings.postBuildHook != "") {
-            Activity act(*logger, lvlInfo, actPostBuildHook,
-                fmt("running post-build-hook '%s'", settings.postBuildHook),
-                Logger::Fields{worker.store.printStorePath(drvPath)});
-            PushActivity pact(act.id);
-            StorePathSet outputPaths;
-            for (auto i : drv->outputs) {
-                outputPaths.insert(finalOutputs.at(i.first));
-            }
-            std::map<std::string, std::string> hookEnvironment = getEnv();
-
-            hookEnvironment.emplace("DRV_PATH", worker.store.printStorePath(drvPath));
-            hookEnvironment.emplace("OUT_PATHS", chomp(concatStringsSep(" ", worker.store.printStorePathSet(outputPaths))));
-
-            RunOptions opts(settings.postBuildHook, {});
-            opts.environment = hookEnvironment;
-
-            struct LogSink : Sink {
-                Activity & act;
-                std::string currentLine;
-
-                LogSink(Activity & act) : act(act) { }
-
-                void operator() (std::string_view data) override {
-                    for (auto c : data) {
-                        if (c == '\n') {
-                            flushLine();
-                        } else {
-                            currentLine += c;
-                        }
-                    }
-                }
-
-                void flushLine() {
-                    act.result(resPostBuildLogLine, currentLine);
-                    currentLine.clear();
-                }
-
-                ~LogSink() {
-                    if (currentLine != "") {
-                        currentLine += '\n';
-                        flushLine();
-                    }
-                }
-            };
-            LogSink sink(act);
-
-            opts.standardOut = &sink;
-            opts.mergeStderrToStdout = true;
-            runProgram2(opts);
-        }
+        StorePathSet outputPaths;
+        for (auto & [_, path] : finalOutputs)
+            outputPaths.insert(path);
+        runPostBuildHook(
+            worker.store,
+            *logger,
+            drvPath,
+            outputPaths
+        );

        if (buildMode == bmCheck) {
            cleanupPostOutputsRegisteredModeCheck();
@ -909,6 +924,8 @@ void DerivationGoal::resolvedFinished() {

    auto resolvedHashes = staticOutputHashes(worker.store, *resolvedDrv);

+    StorePathSet outputPaths;
+
    // `wantedOutputs` might be empty, which means “all the outputs”
    auto realWantedOutputs = wantedOutputs;
    if (realWantedOutputs.empty())
@ -926,8 +943,10 @@ void DerivationGoal::resolvedFinished() {
            auto newRealisation = *realisation;
            newRealisation.id = DrvOutput{initialOutputs.at(wantedOutput).outputHash, wantedOutput};
            newRealisation.signatures.clear();
+            newRealisation.dependentRealisations = drvOutputReferences(worker.store, *drv, realisation->outPath);
            signRealisation(newRealisation);
            worker.store.registerDrvOutput(newRealisation);
+            outputPaths.insert(realisation->outPath);
        } else {
            // If we don't have a realisation, then it must mean that something
            // failed when building the resolved drv
@ -935,6 +954,13 @@ void DerivationGoal::resolvedFinished() {
        }
    }

+    runPostBuildHook(
+        worker.store,
+        *logger,
+        drvPath,
+        outputPaths
+    );
+
    // This is potentially a bit fishy in terms of error reporting. Not sure
    // how to do it in a cleaner way
    amDone(nrFailed == 0 ? ecSuccess : ecFailed, ex);
--- a/src/libstore/build/drv-output-substitution-goal.cc
+++ b/src/libstore/build/drv-output-substitution-goal.cc
@ -17,6 +17,13 @@ DrvOutputSubstitutionGoal::DrvOutputSubstitutionGoal(const DrvOutput& id, Worker
 void DrvOutputSubstitutionGoal::init()
 {
    trace("init");
+
+    /* If the derivation already exists, we’re done */
+    if (worker.store.queryRealisation(id)) {
+        amDone(ecSuccess);
+        return;
+    }
+
    subs = settings.useSubstitutes ? getDefaultSubstituters() : std::list<ref<Store>>();
    tryNext();
 }
@ -53,6 +60,26 @@ void DrvOutputSubstitutionGoal::tryNext()
        return;
    }

+    for (const auto & [depId, depPath] : outputInfo->dependentRealisations) {
+        if (depId != id) {
+            if (auto localOutputInfo = worker.store.queryRealisation(depId);
+                localOutputInfo && localOutputInfo->outPath != depPath) {
+                warn(
+                    "substituter '%s' has an incompatible realisation for '%s', ignoring.\n"
+                    "Local:  %s\n"
+                    "Remote: %s",
+                    sub->getUri(),
+                    depId.to_string(),
+                    worker.store.printStorePath(localOutputInfo->outPath),
+                    worker.store.printStorePath(depPath)
+                );
+                tryNext();
+                return;
+            }
+            addWaitee(worker.makeDrvOutputSubstitutionGoal(depId));
+        }
+    }
+
    addWaitee(worker.makePathSubstitutionGoal(outputInfo->outPath));

    if (waitees.empty()) outPathValid();
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@ -1248,13 +1248,18 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
    std::optional<const Realisation> queryRealisation(const DrvOutput & id) override
    // XXX: This should probably be allowed if the realisation corresponds to
    // an allowed derivation
-    { throw Error("queryRealisation"); }
+    {
+        if (!goal.isAllowed(id))
+            throw InvalidPath("cannot query an unknown output id '%s' in recursive Nix", id.to_string());
+        return next->queryRealisation(id);
+    }

    void buildPaths(const std::vector<DerivedPath> & paths, BuildMode buildMode) override
    {
        if (buildMode != bmNormal) throw Error("unsupported build mode");

        StorePathSet newPaths;
+        std::set<Realisation> newRealisations;

        for (auto & req : paths) {
            if (!goal.isAllowed(req))
@ -1267,16 +1272,28 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
            auto p =  std::get_if<DerivedPath::Built>(&path);
            if (!p) continue;
            auto & bfd = *p;
+            auto drv = readDerivation(bfd.drvPath);
+            auto drvHashes = staticOutputHashes(*this, drv);
            auto outputs = next->queryDerivationOutputMap(bfd.drvPath);
            for (auto & [outputName, outputPath] : outputs)
-                if (wantOutput(outputName, bfd.outputs))
+                if (wantOutput(outputName, bfd.outputs)) {
                    newPaths.insert(outputPath);
+                    if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+                        auto thisRealisation = next->queryRealisation(
+                            DrvOutput{drvHashes.at(outputName), outputName}
+                        );
+                        assert(thisRealisation);
+                        newRealisations.insert(*thisRealisation);
+                    }
+                }
        }

        StorePathSet closure;
        next->computeFSClosure(newPaths, closure);
        for (auto & path : closure)
            goal.addDependency(path);
+        for (auto & real : Realisation::closure(*next, newRealisations))
+            goal.addedDrvOutputs.insert(real.id);
    }

    BuildResult buildDerivation(const StorePath & drvPath, const BasicDerivation & drv,
@ -2379,6 +2396,7 @@ void LocalDerivationGoal::registerOutputs()
           floating CA derivations and hash-mismatching fixed-output
           derivations. */
        PathLocks dynamicOutputLock;
+        dynamicOutputLock.setDeletion(true);
        auto optFixedPath = output.path(worker.store, drv->name, outputName);
        if (!optFixedPath ||
            worker.store.printStorePath(*optFixedPath) != finalDestPath)
--- a/src/libstore/build/local-derivation-goal.hh
+++ b/src/libstore/build/local-derivation-goal.hh
@ -108,6 +108,9 @@ struct LocalDerivationGoal : public DerivationGoal
    /* Paths that were added via recursive Nix calls. */
    StorePathSet addedPaths;

+    /* Realisations that were added via recursive Nix calls. */
+    std::set<DrvOutput> addedDrvOutputs;
+
    /* Recursive Nix calls are only allowed to build or realize paths
       in the original input closure or added via a recursive Nix call
       (so e.g. you can't do 'nix-store -r /nix/store/<bla>' where
@ -116,6 +119,11 @@ struct LocalDerivationGoal : public DerivationGoal
    {
        return inputPaths.count(path) || addedPaths.count(path);
    }
+    bool isAllowed(const DrvOutput & id)
+    {
+        return addedDrvOutputs.count(id);
+    }
+
    bool isAllowed(const DerivedPath & req);

    friend struct RestrictedStore;
--- a/src/libstore/ca-specific-schema.sql
+++ b/src/libstore/ca-specific-schema.sql
@ -3,10 +3,19 @@
 -- is enabled

 create table if not exists Realisations (
+    id integer primary key autoincrement not null,
    drvPath text not null,
    outputName text not null, -- symbolic output id, usually "out"
    outputPath integer not null,
    signatures text, -- space-separated list
-    primary key (drvPath, outputName),
    foreign key (outputPath) references ValidPaths(id) on delete cascade
 );
+
+create index if not exists IndexRealisations on Realisations(drvPath, outputName);
+
+create table if not exists RealisationsRefs (
+    referrer integer not null,
+    realisationReference integer,
+    foreign key (referrer) references Realisations(id) on delete cascade,
+    foreign key (realisationReference) references Realisations(id) on delete restrict
+);
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@ -53,12 +53,15 @@ struct LocalStore::State::Stmts {
    SQLiteStmt InvalidatePath;
    SQLiteStmt AddDerivationOutput;
    SQLiteStmt RegisterRealisedOutput;
+    SQLiteStmt UpdateRealisedOutput;
    SQLiteStmt QueryValidDerivers;
    SQLiteStmt QueryDerivationOutputs;
    SQLiteStmt QueryRealisedOutput;
    SQLiteStmt QueryAllRealisedOutputs;
    SQLiteStmt QueryPathFromHashPart;
    SQLiteStmt QueryValidPaths;
+    SQLiteStmt QueryRealisationReferences;
+    SQLiteStmt AddRealisationReference;
 };

 int getSchema(Path schemaPath)
@ -76,7 +79,7 @@ int getSchema(Path schemaPath)

 void migrateCASchema(SQLite& db, Path schemaPath, AutoCloseFD& lockFd)
 {
-    const int nixCASchemaVersion = 1;
+    const int nixCASchemaVersion = 2;
    int curCASchema = getSchema(schemaPath);
    if (curCASchema != nixCASchemaVersion) {
        if (curCASchema > nixCASchemaVersion) {
@ -94,7 +97,39 @@ void migrateCASchema(SQLite& db, Path schemaPath, AutoCloseFD& lockFd)
              #include "ca-specific-schema.sql.gen.hh"
                ;
            db.exec(schema);
+            curCASchema = nixCASchemaVersion;
        }
+
+        if (curCASchema < 2) {
+            SQLiteTxn txn(db);
+            // Ugly little sql dance to add a new `id` column and make it the primary key
+            db.exec(R"(
+                create table Realisations2 (
+                    id integer primary key autoincrement not null,
+                    drvPath text not null,
+                    outputName text not null, -- symbolic output id, usually "out"
+                    outputPath integer not null,
+                    signatures text, -- space-separated list
+                    foreign key (outputPath) references ValidPaths(id) on delete cascade
+                );
+                insert into Realisations2 (drvPath, outputName, outputPath, signatures)
+                    select drvPath, outputName, outputPath, signatures from Realisations;
+                drop table Realisations;
+                alter table Realisations2 rename to Realisations;
+            )");
+            db.exec(R"(
+                create index if not exists IndexRealisations on Realisations(drvPath, outputName);
+
+                create table if not exists RealisationsRefs (
+                    referrer integer not null,
+                    realisationReference integer,
+                    foreign key (referrer) references Realisations(id) on delete cascade,
+                    foreign key (realisationReference) references Realisations(id) on delete restrict
+                );
+            )");
+            txn.commit();
+        }
+
        writeFile(schemaPath, fmt("%d", nixCASchemaVersion));
        lockFile(lockFd.get(), ltRead, true);
    }
@ -311,9 +346,18 @@ LocalStore::LocalStore(const Params & params)
                values (?, ?, (select id from ValidPaths where path = ?), ?)
                ;
            )");
+        state->stmts->UpdateRealisedOutput.create(state->db,
+            R"(
+                update Realisations
+                    set signatures = ?
+                where
+                    drvPath = ? and
+                    outputName = ?
+                ;
+            )");
        state->stmts->QueryRealisedOutput.create(state->db,
            R"(
-                select Output.path, Realisations.signatures from Realisations
+                select Realisations.id, Output.path, Realisations.signatures from Realisations
                    inner join ValidPaths as Output on Output.id = Realisations.outputPath
                    where drvPath = ? and outputName = ?
                    ;
@ -325,6 +369,19 @@ LocalStore::LocalStore(const Params & params)
                    where drvPath = ?
                    ;
            )");
+        state->stmts->QueryRealisationReferences.create(state->db,
+            R"(
+                select drvPath, outputName from Realisations
+                    join RealisationsRefs on realisationReference = Realisations.id
+                    where referrer = ?;
+            )");
+        state->stmts->AddRealisationReference.create(state->db,
+            R"(
+                insert or replace into RealisationsRefs (referrer, realisationReference)
+                values (
+                    ?,
+                    (select id from Realisations where drvPath = ? and outputName = ?));
+            )");
    }
 }

@ -661,14 +718,54 @@ void LocalStore::registerDrvOutput(const Realisation & info, CheckSigsFlag check
 void LocalStore::registerDrvOutput(const Realisation & info)
 {
    settings.requireExperimentalFeature("ca-derivations");
-    auto state(_state.lock());
    retrySQLite<void>([&]() {
-        state->stmts->RegisterRealisedOutput.use()
-            (info.id.strHash())
-            (info.id.outputName)
-            (printStorePath(info.outPath))
-            (concatStringsSep(" ", info.signatures))
-            .exec();
+        auto state(_state.lock());
+        if (auto oldR = queryRealisation_(*state, info.id)) {
+            if (info.isCompatibleWith(*oldR)) {
+                auto combinedSignatures = oldR->signatures;
+                combinedSignatures.insert(info.signatures.begin(),
+                    info.signatures.end());
+                state->stmts->UpdateRealisedOutput.use()
+                    (concatStringsSep(" ", combinedSignatures))
+                    (info.id.strHash())
+                    (info.id.outputName)
+                    .exec();
+            } else {
+                throw Error("Trying to register a realisation of '%s', but we already "
+                            "have another one locally.\n"
+                            "Local:  %s\n"
+                            "Remote: %s",
+                    info.id.to_string(),
+                    printStorePath(oldR->outPath),
+                    printStorePath(info.outPath)
+                );
+            }
+        } else {
+            state->stmts->RegisterRealisedOutput.use()
+                (info.id.strHash())
+                (info.id.outputName)
+                (printStorePath(info.outPath))
+                (concatStringsSep(" ", info.signatures))
+                .exec();
+        }
+        uint64_t myId = state->db.getLastInsertedRowId();
+        for (auto & [outputId, depPath] : info.dependentRealisations) {
+            auto localRealisation = queryRealisationCore_(*state, outputId);
+            if (!localRealisation)
+                throw Error("unable to register the derivation '%s' as it "
+                            "depends on the non existent '%s'",
+                    info.id.to_string(), outputId.to_string());
+            if (localRealisation->second.outPath != depPath)
+                throw Error("unable to register the derivation '%s' as it "
+                            "depends on a realisation of '%s' that doesn’t"
+                            "match what we have locally",
+                    info.id.to_string(), outputId.to_string());
+            state->stmts->AddRealisationReference.use()
+                (myId)
+                (outputId.strHash())
+                (outputId.outputName)
+                .exec();
+        }
    });
 }

@ -1679,22 +1776,68 @@ void LocalStore::createUser(const std::string & userName, uid_t userId)
    }
 }

-std::optional<const Realisation> LocalStore::queryRealisation(
-    const DrvOutput& id) {
-    typedef std::optional<const Realisation> Ret;
-    return retrySQLite<Ret>([&]() -> Ret {
-        auto state(_state.lock());
-        auto use(state->stmts->QueryRealisedOutput.use()(id.strHash())(
-            id.outputName));
-        if (!use.next())
-            return std::nullopt;
-        auto outputPath = parseStorePath(use.getStr(0));
-        auto signatures = tokenizeString<StringSet>(use.getStr(1));
-        return Ret{Realisation{
-            .id = id, .outPath = outputPath, .signatures = signatures}};
-    });
+std::optional<std::pair<int64_t, Realisation>> LocalStore::queryRealisationCore_(
+        LocalStore::State & state,
+        const DrvOutput & id)
+{
+    auto useQueryRealisedOutput(
+            state.stmts->QueryRealisedOutput.use()
+                (id.strHash())
+                (id.outputName));
+    if (!useQueryRealisedOutput.next())
+        return std::nullopt;
+    auto realisationDbId = useQueryRealisedOutput.getInt(0);
+    auto outputPath = parseStorePath(useQueryRealisedOutput.getStr(1));
+    auto signatures =
+        tokenizeString<StringSet>(useQueryRealisedOutput.getStr(2));
+
+    return {{
+        realisationDbId,
+        Realisation{
+            .id = id,
+            .outPath = outputPath,
+            .signatures = signatures,
+        }
+    }};
 }

+std::optional<const Realisation> LocalStore::queryRealisation_(
+            LocalStore::State & state,
+            const DrvOutput & id)
+{
+    auto maybeCore = queryRealisationCore_(state, id);
+    if (!maybeCore)
+        return std::nullopt;
+    auto [realisationDbId, res] = *maybeCore;
+
+    std::map<DrvOutput, StorePath> dependentRealisations;
+    auto useRealisationRefs(
+        state.stmts->QueryRealisationReferences.use()
+            (realisationDbId));
+    while (useRealisationRefs.next()) {
+        auto depId = DrvOutput {
+            Hash::parseAnyPrefixed(useRealisationRefs.getStr(0)),
+            useRealisationRefs.getStr(1),
+        };
+        auto dependentRealisation = queryRealisationCore_(state, depId);
+        assert(dependentRealisation); // Enforced by the db schema
+        auto outputPath = dependentRealisation->second.outPath;
+        dependentRealisations.insert({depId, outputPath});
+    }
+
+    res.dependentRealisations = dependentRealisations;
+
+    return { res };
+}
+
+std::optional<const Realisation>
+LocalStore::queryRealisation(const DrvOutput & id)
+{
+    return retrySQLite<std::optional<const Realisation>>([&]() {
+        auto state(_state.lock());
+        return queryRealisation_(*state, id);
+    });
+}

 FixedOutputHash LocalStore::hashCAPath(
    const FileIngestionMethod & method, const HashType & hashType,
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@ -203,6 +203,8 @@ public:
    void registerDrvOutput(const Realisation & info, CheckSigsFlag checkSigs) override;
    void cacheDrvOutputMapping(State & state, const uint64_t deriver, const string & outputName, const StorePath & output);

+    std::optional<const Realisation> queryRealisation_(State & state, const DrvOutput & id);
+    std::optional<std::pair<int64_t, Realisation>> queryRealisationCore_(State & state, const DrvOutput & id);
    std::optional<const Realisation> queryRealisation(const DrvOutput&) override;

 private:
--- a/src/libstore/local.mk
+++ b/src/libstore/local.mk
@ -9,11 +9,11 @@ libstore_SOURCES := $(wildcard $(d)/*.cc $(d)/builtins/*.cc $(d)/build/*.cc)
 libstore_LIBS = libutil

 libstore_LDFLAGS = $(SQLITE3_LIBS) -lbz2 $(LIBCURL_LIBS) $(SODIUM_LIBS) -pthread
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
 libstore_LDFLAGS += -ldl
 endif

-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
 libstore_FILES = sandbox-defaults.sb sandbox-minimal.sb sandbox-network.sb
 endif

@ -23,7 +23,7 @@ ifeq ($(ENABLE_S3), 1)
 	libstore_LDFLAGS += -laws-cpp-sdk-transfer -laws-cpp-sdk-s3 -laws-cpp-sdk-core
 endif

-ifeq ($(OS), SunOS)
+ifdef HOST_SOLARIS
 	libstore_LDFLAGS += -lsocket
 endif

--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@ -16,13 +16,18 @@ Machine::Machine(decltype(storeUri) storeUri,
    decltype(mandatoryFeatures) mandatoryFeatures,
    decltype(sshPublicHostKey) sshPublicHostKey) :
    storeUri(
-        // Backwards compatibility: if the URI is a hostname,
-        // prepend ssh://.
+        // Backwards compatibility: if the URI is schemeless, is not a path,
+        // and is not one of the special store connection words, prepend
+        // ssh://.
        storeUri.find("://") != std::string::npos
-        || hasPrefix(storeUri, "local")
-        || hasPrefix(storeUri, "remote")
-        || hasPrefix(storeUri, "auto")
-        || hasPrefix(storeUri, "/")
+        || storeUri.find("/") != std::string::npos
+        || storeUri == "auto"
+        || storeUri == "daemon"
+        || storeUri == "local"
+        || hasPrefix(storeUri, "auto?")
+        || hasPrefix(storeUri, "daemon?")
+        || hasPrefix(storeUri, "local?")
+        || hasPrefix(storeUri, "?")
        ? storeUri
        : "ssh://" + storeUri),
    systemTypes(systemTypes),
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@ -29,9 +29,9 @@ void Store::computeFSClosure(const StorePathSet & startPaths,
                    res.insert(i);

            if (includeDerivers && path.isDerivation())
-                for (auto& i : queryDerivationOutputs(path))
-                    if (isValidPath(i) && queryPathInfo(i)->deriver == path)
-                        res.insert(i);
+                for (auto& [_, maybeOutPath] : queryPartialDerivationOutputMap(path))
+                    if (maybeOutPath && isValidPath(*maybeOutPath))
+                        res.insert(*maybeOutPath);
            return res;
        };
    else
@ -44,9 +44,9 @@ void Store::computeFSClosure(const StorePathSet & startPaths,
                    res.insert(ref);

            if (includeOutputs && path.isDerivation())
-                for (auto& i : queryDerivationOutputs(path))
-                    if (isValidPath(i))
-                        res.insert(i);
+                for (auto& [_, maybeOutPath] : queryPartialDerivationOutputMap(path))
+                    if (maybeOutPath && isValidPath(*maybeOutPath))
+                        res.insert(*maybeOutPath);

            if (includeDerivers && info->deriver && isValidPath(*info->deriver))
                res.insert(*info->deriver);
@ -254,5 +254,44 @@ StorePaths Store::topoSortPaths(const StorePathSet & paths)
        }});
 }

+std::map<DrvOutput, StorePath> drvOutputReferences(
+    const std::set<Realisation> & inputRealisations,
+    const StorePathSet & pathReferences)
+{
+    std::map<DrvOutput, StorePath> res;

+    for (const auto & input : inputRealisations) {
+        if (pathReferences.count(input.outPath)) {
+            res.insert({input.id, input.outPath});
+        }
+    }
+
+    return res;
+}
+
+std::map<DrvOutput, StorePath> drvOutputReferences(
+    Store & store,
+    const Derivation & drv,
+    const StorePath & outputPath)
+{
+    std::set<Realisation> inputRealisations;
+
+    for (const auto& [inputDrv, outputNames] : drv.inputDrvs) {
+        auto outputHashes =
+            staticOutputHashes(store, store.readDerivation(inputDrv));
+        for (const auto& outputName : outputNames) {
+            auto thisRealisation = store.queryRealisation(
+                DrvOutput{outputHashes.at(outputName), outputName});
+            if (!thisRealisation)
+                throw Error(
+                    "output '%s' of derivation '%s' isn’t built", outputName,
+                    store.printStorePath(inputDrv));
+            inputRealisations.insert(*thisRealisation);
+        }
+    }
+
+    auto info = store.queryPathInfo(outputPath);
+
+    return drvOutputReferences(Realisation::closure(store, inputRealisations), info->references);
+}
 }
--- a/src/libstore/parsed-derivations.cc
+++ b/src/libstore/parsed-derivations.cc
@ -93,6 +93,8 @@ StringSet ParsedDerivation::getRequiredSystemFeatures() const
    StringSet res;
    for (auto & i : getStringsAttr("requiredSystemFeatures").value_or(Strings()))
        res.insert(i);
+    if (!derivationHasKnownOutputPaths(drv.type()))
+        res.insert("ca-derivations");
    return res;
 }

--- a/src/libstore/realisation.cc
+++ b/src/libstore/realisation.cc
@ -1,5 +1,6 @@
 #include "realisation.hh"
 #include "store-api.hh"
+#include "closure.hh"
 #include <nlohmann/json.hpp>

 namespace nix {
@ -21,11 +22,52 @@ std::string DrvOutput::to_string() const {
    return strHash() + "!" + outputName;
 }

+std::set<Realisation> Realisation::closure(Store & store, const std::set<Realisation> & startOutputs)
+{
+    std::set<Realisation> res;
+    Realisation::closure(store, startOutputs, res);
+    return res;
+}
+
+void Realisation::closure(Store & store, const std::set<Realisation> & startOutputs, std::set<Realisation> & res)
+{
+    auto getDeps = [&](const Realisation& current) -> std::set<Realisation> {
+        std::set<Realisation> res;
+        for (auto& [currentDep, _] : current.dependentRealisations) {
+            if (auto currentRealisation = store.queryRealisation(currentDep))
+                res.insert(*currentRealisation);
+            else
+                throw Error(
+                    "Unrealised derivation '%s'", currentDep.to_string());
+        }
+        return res;
+    };
+
+    computeClosure<Realisation>(
+        startOutputs, res,
+        [&](const Realisation& current,
+            std::function<void(std::promise<std::set<Realisation>>&)>
+                processEdges) {
+            std::promise<std::set<Realisation>> promise;
+            try {
+                auto res = getDeps(current);
+                promise.set_value(res);
+            } catch (...) {
+                promise.set_exception(std::current_exception());
+            }
+            return processEdges(promise);
+        });
+}
+
 nlohmann::json Realisation::toJSON() const {
+    auto jsonDependentRealisations = nlohmann::json::object();
+    for (auto & [depId, depOutPath] : dependentRealisations)
+        jsonDependentRealisations.emplace(depId.to_string(), depOutPath.to_string());
    return nlohmann::json{
        {"id", id.to_string()},
        {"outPath", outPath.to_string()},
        {"signatures", signatures},
+        {"dependentRealisations", jsonDependentRealisations},
    };
 }

@ -51,10 +93,16 @@ Realisation Realisation::fromJSON(
    if (auto signaturesIterator = json.find("signatures"); signaturesIterator != json.end())
        signatures.insert(signaturesIterator->begin(), signaturesIterator->end());

+    std::map <DrvOutput, StorePath> dependentRealisations;
+    if (auto jsonDependencies = json.find("dependentRealisations"); jsonDependencies != json.end())
+        for (auto & [jsonDepId, jsonDepOutPath] : jsonDependencies->get<std::map<std::string, std::string>>())
+            dependentRealisations.insert({DrvOutput::parse(jsonDepId), StorePath(jsonDepOutPath)});
+
    return Realisation{
        .id = DrvOutput::parse(getField("id")),
        .outPath = StorePath(getField("outPath")),
        .signatures = signatures,
+        .dependentRealisations = dependentRealisations,
    };
 }

@ -92,6 +140,16 @@ StorePath RealisedPath::path() const {
    return std::visit([](auto && arg) { return arg.getPath(); }, raw);
 }

+bool Realisation::isCompatibleWith(const Realisation & other) const
+{
+    assert (id == other.id);
+    if (outPath == other.outPath) {
+        assert(dependentRealisations == other.dependentRealisations);
+        return true;
+    }
+    return false;
+}
+
 void RealisedPath::closure(
    Store& store,
    const RealisedPath::Set& startPaths,
--- a/src/libstore/realisation.hh
+++ b/src/libstore/realisation.hh
@ -28,6 +28,14 @@ struct Realisation {

    StringSet signatures;

+    /**
+     * The realisations that are required for the current one to be valid.
+     *
+     * When importing this realisation, the store will first check that all its
+     * dependencies exist, and map to the correct output path
+     */
+    std::map<DrvOutput, StorePath> dependentRealisations;
+
    nlohmann::json toJSON() const;
    static Realisation fromJSON(const nlohmann::json& json, const std::string& whence);

@ -36,6 +44,11 @@ struct Realisation {
    bool checkSignature(const PublicKeys & publicKeys, const std::string & sig) const;
    size_t checkSignatures(const PublicKeys & publicKeys) const;

+    static std::set<Realisation> closure(Store &, const std::set<Realisation> &);
+    static void closure(Store &, const std::set<Realisation> &, std::set<Realisation>& res);
+
+    bool isCompatibleWith(const Realisation & other) const;
+
    StorePath getPath() const { return outPath; }

    GENERATE_CMP(Realisation, me->id, me->outPath);
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@ -337,6 +337,13 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
    return info;
 }

+StringSet StoreConfig::getDefaultSystemFeatures()
+{
+    auto res = settings.systemFeatures.get();
+    if (settings.isExperimentalFeatureEnabled("ca-derivations"))
+        res.insert("ca-derivations");
+    return res;
+}

 Store::Store(const Params & params)
    : StoreConfig(params)
@ -816,20 +823,39 @@ std::map<StorePath, StorePath> copyPaths(ref<Store> srcStore, ref<Store> dstStor
    RepairFlag repair, CheckSigsFlag checkSigs, SubstituteFlag substitute)
 {
    StorePathSet storePaths;
-    std::set<Realisation> realisations;
+    std::set<Realisation> toplevelRealisations;
    for (auto & path : paths) {
        storePaths.insert(path.path());
        if (auto realisation = std::get_if<Realisation>(&path.raw)) {
            settings.requireExperimentalFeature("ca-derivations");
-            realisations.insert(*realisation);
+            toplevelRealisations.insert(*realisation);
        }
    }
    auto pathsMap = copyPaths(srcStore, dstStore, storePaths, repair, checkSigs, substitute);
+
+    ThreadPool pool;
+
    try {
-        for (auto & realisation : realisations) {
-            dstStore->registerDrvOutput(realisation, checkSigs);
-        }
-    } catch (MissingExperimentalFeature & e) {
+        // Copy the realisation closure
+        processGraph<Realisation>(
+            pool, Realisation::closure(*srcStore, toplevelRealisations),
+            [&](const Realisation& current) -> std::set<Realisation> {
+                std::set<Realisation> children;
+                for (const auto& [drvOutput, _] : current.dependentRealisations) {
+                    auto currentChild = srcStore->queryRealisation(drvOutput);
+                    if (!currentChild)
+                        throw Error(
+                            "Incomplete realisation closure: '%s' is a "
+                            "dependency of '%s' but isn’t registered",
+                            drvOutput.to_string(), current.id.to_string());
+                    children.insert(*currentChild);
+                }
+                return children;
+            },
+            [&](const Realisation& current) -> void {
+                dstStore->registerDrvOutput(current, checkSigs);
+            });
+    } catch (MissingExperimentalFeature& e) {
        // Don't fail if the remote doesn't support CA derivations is it might
        // not be within our control to change that, and we might still want
        // to at least copy the output paths.
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@ -180,6 +180,8 @@ struct StoreConfig : public Config

    StoreConfig() = delete;

+    StringSet getDefaultSystemFeatures();
+
    virtual ~StoreConfig() { }

    virtual const std::string name() = 0;
@ -196,7 +198,7 @@ struct StoreConfig : public Config

    Setting<bool> wantMassQuery{this, false, "want-mass-query", "whether this substituter can be queried efficiently for path validity"};

-    Setting<StringSet> systemFeatures{this, settings.systemFeatures,
+    Setting<StringSet> systemFeatures{this, getDefaultSystemFeatures(),
        "system-features",
        "Optional features that the system this store builds on implements (like \"kvm\")."};

@ -869,4 +871,9 @@ std::pair<std::string, Store::Params> splitUriAndParams(const std::string & uri)

 std::optional<ContentAddress> getDerivationCA(const BasicDerivation & drv);

+std::map<DrvOutput, StorePath> drvOutputReferences(
+    Store & store,
+    const Derivation & drv,
+    const StorePath & outputPath);
+
 }
--- a/src/libutil/comparator.hh
+++ b/src/libutil/comparator.hh
@ -25,6 +25,8 @@
    }
 #define GENERATE_EQUAL(args...) GENERATE_ONE_CMP(==, args)
 #define GENERATE_LEQ(args...) GENERATE_ONE_CMP(<, args)
+#define GENERATE_NEQ(args...) GENERATE_ONE_CMP(!=, args)
 #define GENERATE_CMP(args...) \
    GENERATE_EQUAL(args) \
-    GENERATE_LEQ(args)
+    GENERATE_LEQ(args) \
+    GENERATE_NEQ(args)
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@ -46,7 +46,7 @@ public:
        : printBuildLogs(printBuildLogs)
    {
        systemd = getEnv("IN_SYSTEMD") == "1";
-        tty = isatty(STDERR_FILENO);
+        tty = shouldANSI();
    }

    bool isVerbose() override {
--- a/src/libutil/url.cc
+++ b/src/libutil/url.cc
@ -32,7 +32,7 @@ ParsedURL parseURL(const std::string & url)
        auto isFile = scheme.find("file") != std::string::npos;

        if (authority && *authority != "" && isFile)
-            throw Error("file:// URL '%s' has unexpected authority '%s'",
+            throw BadURL("file:// URL '%s' has unexpected authority '%s'",
                url, *authority);

        if (isFile && path.empty())
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@ -1372,6 +1372,12 @@ void ignoreException()
    }
 }

+bool shouldANSI()
+{
+    return isatty(STDERR_FILENO)
+        && getEnv("TERM").value_or("dumb") != "dumb"
+        && !getEnv("NO_COLOR").has_value();
+}

 std::string filterANSIEscapes(const std::string & s, bool filterAll, unsigned int width)
 {
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@ -482,6 +482,9 @@ constexpr char treeLast[] = "└───";
 constexpr char treeLine[] = "│   ";
 constexpr char treeNull[] = "    ";

+/* Determine whether ANSI escape sequences are appropriate for the
+   present output. */
+bool shouldANSI();

 /* Truncate a string to 'width' printable characters. If 'filterAll'
   is true, all ANSI escape sequences are filtered out. Otherwise,
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@ -392,6 +392,12 @@ static void main_nix_build(int argc, char * * argv)

        if (dryRun) return;

+        if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+            auto resolvedDrv = drv.tryResolve(*store);
+            assert(resolvedDrv && "Successfully resolved the derivation");
+            drv = *resolvedDrv;
+        }
+
        // Set the environment.
        auto env = getEnv();

--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@ -8,7 +8,7 @@
 #include "affinity.hh"
 #include "progress-bar.hh"

-#include <regex>
+#include <nlohmann/json.hpp>

 using namespace nix;

@ -25,94 +25,142 @@ static DevelopSettings developSettings;

 static GlobalConfig::Register rDevelopSettings(&developSettings);

-struct Var
-{
-    bool exported = true;
-    bool associative = false;
-    std::string quoted; // quoted string or array
-};
-
 struct BuildEnvironment
 {
-    std::map<std::string, Var> env;
-    std::string bashFunctions;
-};
+    struct String
+    {
+        bool exported;
+        std::string value;

-BuildEnvironment readEnvironment(const Path & path)
-{
-    BuildEnvironment res;
+        bool operator == (const String & other) const
+        {
+            return exported == other.exported && value == other.value;
+        }
+    };

-    std::set<std::string> exported;
+    using Array = std::vector<std::string>;

-    debug("reading environment file '%s'", path);
+    using Associative = std::map<std::string, std::string>;

-    auto file = readFile(path);
+    using Value = std::variant<String, Array, Associative>;

-    auto pos = file.cbegin();
+    std::map<std::string, Value> vars;
+    std::map<std::string, std::string> bashFunctions;

-    static std::string varNameRegex =
-        R"re((?:[a-zA-Z_][a-zA-Z0-9_]*))re";
+    static BuildEnvironment fromJSON(std::string_view in)
+    {
+        BuildEnvironment res;

-    static std::string simpleStringRegex =
-        R"re((?:[a-zA-Z0-9_/:\.\-\+=]*))re";
+        std::set<std::string> exported;

-    static std::string dquotedStringRegex =
-        R"re((?:\$?"(?:[^"\\]|\\[$`"\\\n])*"))re";
+        auto json = nlohmann::json::parse(in);

-    static std::string squotedStringRegex =
-        R"re((?:\$?(?:'(?:[^'\\]|\\[abeEfnrtv\\'"?])*'|\\')+))re";
-
-    static std::string indexedArrayRegex =
-        R"re((?:\(( *\[[0-9]+\]="(?:[^"\\]|\\.)*")*\)))re";
-
-    static std::regex declareRegex(
-        "^declare -a?x (" + varNameRegex + ")(=(" +
-        dquotedStringRegex + "|" + indexedArrayRegex + "))?\n");
-
-    static std::regex varRegex(
-        "^(" + varNameRegex + ")=(" + simpleStringRegex + "|" + squotedStringRegex + "|" + indexedArrayRegex + ")\n");
-
-    /* Note: we distinguish between an indexed and associative array
-       using the space before the closing parenthesis. Will
-       undoubtedly regret this some day. */
-    static std::regex assocArrayRegex(
-        "^(" + varNameRegex + ")=" + R"re((?:\(( *\[[^\]]+\]="(?:[^"\\]|\\.)*")* *\)))re" + "\n");
-
-    static std::regex functionRegex(
-        "^" + varNameRegex + " \\(\\) *\n");
-
-    while (pos != file.end()) {
-
-        std::smatch match;
-
-        if (std::regex_search(pos, file.cend(), match, declareRegex, std::regex_constants::match_continuous)) {
-            pos = match[0].second;
-            exported.insert(match[1]);
+        for (auto & [name, info] : json["variables"].items()) {
+            std::string type = info["type"];
+            if (type == "var" || type == "exported")
+                res.vars.insert({name, BuildEnvironment::String { .exported = type == "exported", .value = info["value"] }});
+            else if (type == "array")
+                res.vars.insert({name, (Array) info["value"]});
+            else if (type == "associative")
+                res.vars.insert({name, (Associative) info["value"]});
        }

-        else if (std::regex_search(pos, file.cend(), match, varRegex, std::regex_constants::match_continuous)) {
-            pos = match[0].second;
-            res.env.insert({match[1], Var { .exported = exported.count(match[1]) > 0, .quoted = match[2] }});
+        for (auto & [name, def] : json["bashFunctions"].items()) {
+            res.bashFunctions.insert({name, def});
        }

-        else if (std::regex_search(pos, file.cend(), match, assocArrayRegex, std::regex_constants::match_continuous)) {
-            pos = match[0].second;
-            res.env.insert({match[1], Var { .associative = true, .quoted = match[2] }});
-        }
-
-        else if (std::regex_search(pos, file.cend(), match, functionRegex, std::regex_constants::match_continuous)) {
-            res.bashFunctions = std::string(pos, file.cend());
-            break;
-        }
-
-        else throw Error("shell environment '%s' has unexpected line '%s'",
-            path, file.substr(pos - file.cbegin(), 60));
+        return res;
    }

-    res.env.erase("__output");
+    std::string toJSON() const
+    {
+        auto res = nlohmann::json::object();

-    return res;
-}
+        auto vars2 = nlohmann::json::object();
+        for (auto & [name, value] : vars) {
+            auto info = nlohmann::json::object();
+            if (auto str = std::get_if<String>(&value)) {
+                info["type"] = str->exported ? "exported" : "var";
+                info["value"] = str->value;
+            }
+            else if (auto arr = std::get_if<Array>(&value)) {
+                info["type"] = "array";
+                info["value"] = *arr;
+            }
+            else if (auto arr = std::get_if<Associative>(&value)) {
+                info["type"] = "associative";
+                info["value"] = *arr;
+            }
+            vars2[name] = std::move(info);
+        }
+        res["variables"] = std::move(vars2);
+
+        res["bashFunctions"] = bashFunctions;
+
+        auto json = res.dump();
+
+        assert(BuildEnvironment::fromJSON(json) == *this);
+
+        return json;
+    }
+
+    void toBash(std::ostream & out, const std::set<std::string> & ignoreVars) const
+    {
+        for (auto & [name, value] : vars) {
+            if (!ignoreVars.count(name)) {
+                if (auto str = std::get_if<String>(&value)) {
+                    out << fmt("%s=%s\n", name, shellEscape(str->value));
+                    if (str->exported)
+                        out << fmt("export %s\n", name);
+                }
+                else if (auto arr = std::get_if<Array>(&value)) {
+                    out << "declare -a " << name << "=(";
+                    for (auto & s : *arr)
+                        out << shellEscape(s) << " ";
+                    out << ")\n";
+                }
+                else if (auto arr = std::get_if<Associative>(&value)) {
+                    out << "declare -A " << name << "=(";
+                    for (auto & [n, v] : *arr)
+                        out << "[" << shellEscape(n) << "]=" << shellEscape(v) << " ";
+                    out << ")\n";
+                }
+            }
+        }
+
+        for (auto & [name, def] : bashFunctions) {
+            out << name << " ()\n{\n" << def << "}\n";
+        }
+    }
+
+    static std::string getString(const Value & value)
+    {
+        if (auto str = std::get_if<String>(&value))
+            return str->value;
+        else
+            throw Error("bash variable is not a string");
+    }
+
+    static Array getStrings(const Value & value)
+    {
+        if (auto str = std::get_if<String>(&value))
+            return tokenizeString<Array>(str->value);
+        else if (auto arr = std::get_if<Array>(&value)) {
+            return *arr;
+        } else if (auto assoc = std::get_if<Associative>(&value)) {
+            Array assocKeys;
+            std::for_each(assoc->begin(), assoc->end(), [&](auto & n) { assocKeys.push_back(n.first); });
+            return assocKeys;
+        }
+        else
+            throw Error("bash variable is not a string or array");
+    }
+
+    bool operator == (const BuildEnvironment & other) const
+    {
+        return vars == other.vars && bashFunctions == other.bashFunctions;
+    }
+};

 const static std::string getEnvSh =
    #include "get-env.sh.gen.hh"
@ -144,17 +192,26 @@ StorePath getDerivationEnvironment(ref<Store> store, const StorePath & drvPath)
    /* Rehash and write the derivation. FIXME: would be nice to use
       'buildDerivation', but that's privileged. */
    drv.name += "-env";
-    for (auto & output : drv.outputs) {
-        output.second = { .output = DerivationOutputInputAddressed { .path = StorePath::dummy } };
-        drv.env[output.first] = "";
-    }
    drv.inputSrcs.insert(std::move(getEnvShPath));
-    Hash h = std::get<0>(hashDerivationModulo(*store, drv, true));
+    if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
+        for (auto & output : drv.outputs) {
+            output.second = {
+                .output = DerivationOutputDeferred{},
+            };
+            drv.env[output.first] = hashPlaceholder(output.first);
+        }
+    } else {
+        for (auto & output : drv.outputs) {
+            output.second = { .output = DerivationOutputInputAddressed { .path = StorePath::dummy } };
+            drv.env[output.first] = "";
+        }
+        Hash h = std::get<0>(hashDerivationModulo(*store, drv, true));

-    for (auto & output : drv.outputs) {
-        auto outPath = store->makeOutputPath(output.first, h, drv.name);
-        output.second = { .output = DerivationOutputInputAddressed { .path = outPath } };
-        drv.env[output.first] = store->printStorePath(outPath);
+        for (auto & output : drv.outputs) {
+            auto outPath = store->makeOutputPath(output.first, h, drv.name);
+            output.second = { .output = DerivationOutputInputAddressed { .path = outPath } };
+            drv.env[output.first] = store->printStorePath(outPath);
+        }
    }

    auto shellDrvPath = writeDerivation(*store, drv);
@ -162,8 +219,7 @@ StorePath getDerivationEnvironment(ref<Store> store, const StorePath & drvPath)
    /* Build the derivation. */
    store->buildPaths({DerivedPath::Built{shellDrvPath}});

-    for (auto & [_0, outputAndOptPath] : drv.outputsAndOptPaths(*store)) {
-        auto & [_1, optPath] = outputAndOptPath;
+    for (auto & [_0, optPath] : store->queryPartialDerivationOutputMap(shellDrvPath)) {
        assert(optPath);
        auto & outPath = *optPath;
        assert(store->isValidPath(outPath));
@ -177,19 +233,15 @@ StorePath getDerivationEnvironment(ref<Store> store, const StorePath & drvPath)

 struct Common : InstallableCommand, MixProfile
 {
-    std::set<string> ignoreVars{
+    std::set<std::string> ignoreVars{
        "BASHOPTS",
-        "EUID",
        "HOME", // FIXME: don't ignore in pure mode?
-        "HOSTNAME",
        "NIX_BUILD_TOP",
        "NIX_ENFORCE_PURITY",
        "NIX_LOG_FD",
        "NIX_REMOTE",
        "PPID",
-        "PWD",
        "SHELLOPTS",
-        "SHLVL",
        "SSL_CERT_FILE", // FIXME: only want to ignore /no-cert-file.crt
        "TEMP",
        "TEMPDIR",
@ -225,22 +277,10 @@ struct Common : InstallableCommand, MixProfile

        out << "nix_saved_PATH=\"$PATH\"\n";

-        for (auto & i : buildEnvironment.env) {
-            if (!ignoreVars.count(i.first) && !hasPrefix(i.first, "BASH_")) {
-                if (i.second.associative)
-                    out << fmt("declare -A %s=(%s)\n", i.first, i.second.quoted);
-                else {
-                    out << fmt("%s=%s\n", i.first, i.second.quoted);
-                    if (i.second.exported)
-                        out << fmt("export %s\n", i.first);
-                }
-            }
-        }
+        buildEnvironment.toBash(out, ignoreVars);

        out << "PATH=\"$PATH:$nix_saved_PATH\"\n";

-        out << buildEnvironment.bashFunctions << "\n";
-
        out << "export NIX_BUILD_TOP=\"$(mktemp -d -t nix-shell.XXXXXX)\"\n";
        for (auto & i : {"TMP", "TMPDIR", "TEMP", "TEMPDIR"})
            out << fmt("export %s=\"$NIX_BUILD_TOP\"\n", i);
@ -250,24 +290,16 @@ struct Common : InstallableCommand, MixProfile
        auto script = out.str();

        /* Substitute occurrences of output paths. */
-        auto outputs = buildEnvironment.env.find("outputs");
-        assert(outputs != buildEnvironment.env.end());
+        auto outputs = buildEnvironment.vars.find("outputs");
+        assert(outputs != buildEnvironment.vars.end());

        // FIXME: properly unquote 'outputs'.
        StringMap rewrites;
-        for (auto & outputName : tokenizeString<std::vector<std::string>>(replaceStrings(outputs->second.quoted, "'", ""))) {
-            // Hacky way to obtain the key of an associate array. This is needed for strctured attrs where
-            // `outputs` is an associative array. If the regex isn't matched, the non-structured-attrs behavior will
-            // be used.
-            std::regex ptrn(R"re(\[([A-z0-9]+)\]=.*)re");
-            std::smatch match;
-            if (std::regex_match(outputName, match, ptrn)) {
-                outputName = match[1];
-            }
-            auto from = buildEnvironment.env.find(outputName);
-            assert(from != buildEnvironment.env.end());
+        for (auto & outputName : BuildEnvironment::getStrings(outputs->second)) {
+            auto from = buildEnvironment.vars.find(outputName);
+            assert(from != buildEnvironment.vars.end());
            // FIXME: unquote
-            rewrites.insert({from->second.quoted, outputsDir + "/" + outputName});
+            rewrites.insert({BuildEnvironment::getString(from->second), outputsDir + "/" + outputName});
        }

        /* Substitute redirects. */
@ -321,7 +353,9 @@ struct Common : InstallableCommand, MixProfile

        updateProfile(shellOutPath);

-        return {readEnvironment(strPath), strPath};
+        debug("reading environment file '%s'", strPath);
+
+        return {BuildEnvironment::fromJSON(readFile(strPath)), strPath};
    }
 };

@ -443,13 +477,17 @@ struct CmdDevelop : Common, MixEnvironment
        try {
            auto state = getEvalState();

+            auto nixpkgsLockFlags = lockFlags;
+            nixpkgsLockFlags.inputOverrides = {};
+            nixpkgsLockFlags.inputUpdates = {};
+
            auto bashInstallable = std::make_shared<InstallableFlake>(
                this,
                state,
                installable->nixpkgsFlakeRef(),
                Strings{"bashInteractive"},
                Strings{"legacyPackages." + settings.thisSystem.get() + "."},
-                lockFlags);
+                nixpkgsLockFlags);

            shell = state->store->printStorePath(
                toStorePath(state->store, Realise::Outputs, OperateOn::Output, bashInstallable)) + "/bin/bash";
@ -470,7 +508,7 @@ struct CmdDevelop : Common, MixEnvironment
    }
 };

-struct CmdPrintDevEnv : Common
+struct CmdPrintDevEnv : Common, MixJSON
 {
    std::string description() override
    {
@ -492,7 +530,10 @@ struct CmdPrintDevEnv : Common

        stopProgressBar();

-        std::cout << makeRcScript(store, buildEnvironment);
+        logger->writeToStdout(
+            json
+            ? buildEnvironment.toJSON()
+            : makeRcScript(store, buildEnvironment));
    }
 };

--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@ -84,6 +84,7 @@ struct CmdFlakeUpdate : FlakeCommand

        lockFlags.recreateLockFile = true;
        lockFlags.writeLockFile = true;
+        lockFlags.applyNixConfig = true;

        lockFlake();
    }
@ -114,6 +115,7 @@ struct CmdFlakeLock : FlakeCommand
        settings.tarballTtl = 0;

        lockFlags.writeLockFile = true;
+        lockFlags.applyNixConfig = true;

        lockFlake();
    }
@ -270,6 +272,8 @@ struct CmdFlakeCheck : FlakeCommand
        settings.readOnlyMode = !build;

        auto state = getEvalState();
+
+        lockFlags.applyNixConfig = true;
        auto flake = lockFlake();

        bool hasErrors = false;
--- a/src/nix/get-env.sh
+++ b/src/nix/get-env.sh
@ -8,6 +8,109 @@ if [[ -n $stdenv ]]; then
    source $stdenv/setup
 fi

+# Better to use compgen, but stdenv bash doesn't have it.
+__vars="$(declare -p)"
+__functions="$(declare -F)"
+
+__dumpEnv() {
+    printf '{\n'
+
+    printf '  "bashFunctions": {\n'
+    local __first=1
+    while read __line; do
+        if ! [[ $__line =~ ^declare\ -f\ (.*) ]]; then continue; fi
+        __fun_name="${BASH_REMATCH[1]}"
+        __fun_body="$(type $__fun_name)"
+        if [[ $__fun_body =~ \{(.*)\} ]]; then
+            if [[ -z $__first ]]; then printf ',\n'; else __first=; fi
+            __fun_body="${BASH_REMATCH[1]}"
+            printf "    "
+            __escapeString "$__fun_name"
+            printf ':'
+            __escapeString "$__fun_body"
+        else
+            printf "Cannot parse definition of function '%s'.\n" "$__fun_name" >&2
+            return 1
+        fi
+    done < <(printf "%s\n" "$__functions")
+    printf '\n  },\n'
+
+    printf '  "variables": {\n'
+    local __first=1
+    while read __line; do
+        if ! [[ $__line =~ ^declare\ (-[^ ])\ ([^=]*) ]]; then continue; fi
+        local type="${BASH_REMATCH[1]}"
+        local __var_name="${BASH_REMATCH[2]}"
+
+        if [[ $__var_name =~ ^BASH_ || \
+              $__var_name = _ || \
+              $__var_name = DIRSTACK || \
+              $__var_name = EUID || \
+              $__var_name = FUNCNAME || \
+              $__var_name = HISTCMD || \
+              $__var_name = HOSTNAME || \
+              $__var_name = GROUPS || \
+              $__var_name = PIPESTATUS || \
+              $__var_name = PWD || \
+              $__var_name = RANDOM || \
+              $__var_name = SHLVL || \
+              $__var_name = SECONDS \
+            ]]; then continue; fi
+
+        if [[ -z $__first ]]; then printf ',\n'; else __first=; fi
+
+        printf "    "
+        __escapeString "$__var_name"
+        printf ': {'
+
+        # FIXME: handle -i, -r, -n.
+        if [[ $type == -x ]]; then
+            printf '"type": "exported", "value": '
+            __escapeString "${!__var_name}"
+        elif [[ $type == -- ]]; then
+            printf '"type": "var", "value": '
+            __escapeString "${!__var_name}"
+        elif [[ $type == -a ]]; then
+            printf '"type": "array", "value": ['
+            local __first2=1
+            __var_name="$__var_name[@]"
+            for __i in "${!__var_name}"; do
+                if [[ -z $__first2 ]]; then printf ', '; else __first2=; fi
+                __escapeString "$__i"
+                printf ' '
+            done
+            printf ']'
+        elif [[ $type == -A ]]; then
+            printf '"type": "associative", "value": {\n'
+            local __first2=1
+            declare -n __var_name2="$__var_name"
+            for __i in "${!__var_name2[@]}"; do
+                if [[ -z $__first2 ]]; then printf ',\n'; else __first2=; fi
+                printf "      "
+                __escapeString "$__i"
+                printf ": "
+                __escapeString "${__var_name2[$__i]}"
+            done
+            printf '\n    }'
+        else
+            printf '"type": "unknown"'
+        fi
+
+        printf "}"
+    done < <(printf "%s\n" "$__vars")
+    printf '\n  }\n}'
+}
+
+__escapeString() {
+    local __s="$1"
+    __s="${__s//\\/\\\\}"
+    __s="${__s//\"/\\\"}"
+    __s="${__s//$'\n'/\\n}"
+    __s="${__s//$'\r'/\\r}"
+    __s="${__s//$'\t'/\\t}"
+    printf '"%s"' "$__s"
+}
+
 # In case of `__structuredAttrs = true;` the list of outputs is an associative
 # array with a format like `outname => /nix/store/hash-drvname-outname`, so `__olist`
 # must contain the array's keys (hence `${!...[@]}`) in this case.
@ -19,8 +122,7 @@ fi

 for __output in $__olist; do
    if [[ -z $__done ]]; then
-        export > "${!__output}"
-        set >> "${!__output}"
+        __dumpEnv > ${!__output}
        __done=1
    else
        echo -n >> "${!__output}"
--- a/src/nix/print-dev-env.md
+++ b/src/nix/print-dev-env.md
@ -8,12 +8,43 @@ R""(
  # . <(nix print-dev-env nixpkgs#hello)
  ```

+* Get the build environment in JSON format:
+
+  ```console
+  # nix print-dev-env nixpkgs#hello --json
+  ```
+
+  The output will look like this:
+
+  ```json
+  {
+    "bashFunctions": {
+      "buildPhase": " \n    runHook preBuild;\n...",
+      ...
+    },
+    "variables": {
+      "src": {
+        "type": "exported",
+        "value": "/nix/store/3x7dwzq014bblazs7kq20p9hyzz0qh8g-hello-2.10.tar.gz"
+      },
+      "postUnpackHooks": {
+        "type": "array",
+        "value": ["_updateSourceDateEpochFromSourceRoot"]
+      },
+      ...
+    }
+  }
+  ```
+
 # Description

-This command prints a shell script that can be sourced by `b`ash and
-that sets the environment variables and shell functions defined by the
-build process of *installable*. This allows you to get a similar build
+This command prints a shell script that can be sourced by `bash` and
+that sets the variables and shell functions defined by the build
+process of *installable*. This allows you to get a similar build
 environment in your current shell rather than in a subshell (as with
 `nix develop`).

+With `--json`, the output is a JSON serialisation of the variables and
+functions defined by the build process.
+
 )""
--- a/src/nix/profile-remove.md
+++ b/src/nix/profile-remove.md
@ -15,6 +15,7 @@ R""(
  ```

 * Remove all packages:
+
  ```console
  # nix profile remove '.*'
  ```
--- a/src/nix/registry-add.md
+++ b/src/nix/registry-add.md
@ -21,6 +21,13 @@ R""(
  # nix registry add nixpkgs/nixos-20.03 ~/Dev/nixpkgs
  ```

+* Add `nixpkgs` pointing to `github:nixos/nixpkgs` to your custom flake
+  registry:
+
+  ```console
+  nix registry add --registry ./custom-flake-registry.json nixpkgs github:nixos/nixpkgs
+  ```
+
 # Description

 This command adds an entry to the user registry that maps flake
--- a/src/nix/registry-pin.md
+++ b/src/nix/registry-pin.md
@ -24,6 +24,13 @@ R""(
  …
  ```

+* Pin `nixpkgs` in a custom registry to its most recent Git revision:
+
+  ```console
+  # nix registry pin --registry ./custom-flake-registry.json nixpkgs
+  ```
+
+
 # Description

 This command adds an entry to the user registry that maps flake
--- a/src/nix/registry-remove.md
+++ b/src/nix/registry-remove.md
@ -8,6 +8,12 @@ R""(
  # nix registry remove nixpkgs
  ```

+* Remove the entry `nixpkgs` from a custom registry:
+
+  ```console
+  # nix registry remove --registry ./custom-flake-registry.json nixpkgs
+  ```
+
 # Description

 This command removes from the user registry any entry for flake
--- a/src/nix/registry.cc
+++ b/src/nix/registry.cc
@ -10,6 +10,46 @@
 using namespace nix;
 using namespace nix::flake;

+
+class RegistryCommand : virtual Args
+{
+    std::string registry_path;
+
+    std::shared_ptr<fetchers::Registry> registry;
+
+public:
+
+    RegistryCommand()
+    {
+        addFlag({
+            .longName = "registry",
+            .description = "The registry to operate on.",
+            .labels = {"registry"},
+            .handler = {&registry_path},
+        });
+    }
+
+    std::shared_ptr<fetchers::Registry> getRegistry()
+    {
+        if (registry) return registry;
+        if (registry_path.empty()) {
+            registry = fetchers::getUserRegistry();
+        } else {
+            registry = fetchers::getCustomRegistry(registry_path);
+        }
+        return registry;
+    }
+
+    Path getRegistryPath()
+    {
+        if (registry_path.empty()) {
+            return fetchers::getUserRegistryPath();
+        } else {
+            return registry_path;
+        }
+    }
+};
+
 struct CmdRegistryList : StoreCommand
 {
    std::string description() override
@ -45,7 +85,7 @@ struct CmdRegistryList : StoreCommand
    }
 };

-struct CmdRegistryAdd : MixEvalArgs, Command
+struct CmdRegistryAdd : MixEvalArgs, Command, RegistryCommand
 {
    std::string fromUrl, toUrl;

@ -71,16 +111,16 @@ struct CmdRegistryAdd : MixEvalArgs, Command
    {
        auto fromRef = parseFlakeRef(fromUrl);
        auto toRef = parseFlakeRef(toUrl);
+        auto registry = getRegistry();
        fetchers::Attrs extraAttrs;
        if (toRef.subdir != "") extraAttrs["dir"] = toRef.subdir;
-        auto userRegistry = fetchers::getUserRegistry();
-        userRegistry->remove(fromRef.input);
-        userRegistry->add(fromRef.input, toRef.input, extraAttrs);
-        userRegistry->write(fetchers::getUserRegistryPath());
+        registry->remove(fromRef.input);
+        registry->add(fromRef.input, toRef.input, extraAttrs);
+        registry->write(getRegistryPath());
    }
 };

-struct CmdRegistryRemove : virtual Args, MixEvalArgs, Command
+struct CmdRegistryRemove : RegistryCommand, Command
 {
    std::string url;

@ -103,19 +143,21 @@ struct CmdRegistryRemove : virtual Args, MixEvalArgs, Command

    void run() override
    {
-        auto userRegistry = fetchers::getUserRegistry();
-        userRegistry->remove(parseFlakeRef(url).input);
-        userRegistry->write(fetchers::getUserRegistryPath());
+        auto registry = getRegistry();
+        registry->remove(parseFlakeRef(url).input);
+        registry->write(getRegistryPath());
    }
 };

-struct CmdRegistryPin : virtual Args, EvalCommand
+struct CmdRegistryPin : RegistryCommand, EvalCommand
 {
    std::string url;

+    std::string locked;
+
    std::string description() override
    {
-        return "pin a flake to its current version in user flake registry";
+        return "pin a flake to its current version or to the current version of a flake URL";
    }

    std::string doc() override
@ -128,18 +170,31 @@ struct CmdRegistryPin : virtual Args, EvalCommand
    CmdRegistryPin()
    {
        expectArg("url", &url);
+
+        expectArgs({
+            .label = "locked",
+            .optional = true,
+            .handler = {&locked},
+            .completer = {[&](size_t, std::string_view prefix) {
+                completeFlakeRef(getStore(), prefix);
+            }}
+        });
    }

    void run(nix::ref<nix::Store> store) override
    {
+        if (locked.empty()) {
+            locked = url;
+        }
+        auto registry = getRegistry();
        auto ref = parseFlakeRef(url);
-        auto userRegistry = fetchers::getUserRegistry();
-        userRegistry->remove(ref.input);
-        auto [tree, resolved] = ref.resolve(store).input.fetch(store);
+        auto locked_ref = parseFlakeRef(locked);
+        registry->remove(ref.input);
+        auto [tree, resolved] = locked_ref.resolve(store).input.fetch(store);
        fetchers::Attrs extraAttrs;
        if (ref.subdir != "") extraAttrs["dir"] = ref.subdir;
-        userRegistry->add(ref.input, resolved, extraAttrs);
-        userRegistry->write(fetchers::getUserRegistryPath());
+        registry->add(ref.input, resolved, extraAttrs);
+        registry->write(getRegistryPath());
    }
 };

--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@ -104,6 +104,26 @@ NixRepl::~NixRepl()
    write_history(historyFile.c_str());
 }

+string runNix(Path program, const Strings & args,
+    const std::optional<std::string> & input = {})
+{
+    auto experimentalFeatures = concatStringsSep(" ", settings.experimentalFeatures.get());
+    auto nixConf = getEnv("NIX_CONFIG").value_or("");
+    nixConf.append("\nexperimental-features = " + experimentalFeatures);
+    auto subprocessEnv = getEnv();
+    subprocessEnv["NIX_CONFIG"] = nixConf;
+    RunOptions opts(settings.nixBinDir+ "/" + program, args);
+    opts.input = input;
+    opts.environment = subprocessEnv;
+
+    auto res = runProgram(opts);
+
+    if (!statusOk(res.first))
+        throw ExecError(res.first, fmt("program '%1%' %2%", program, statusToString(res.first)));
+
+    return res.second;
+}
+
 static NixRepl * curRepl; // ugly

 static char * completionCallback(char * s, int *match) {
@ -463,7 +483,7 @@ bool NixRepl::processLine(string line)
        state->callFunction(f, v, result, Pos());

        StorePath drvPath = getDerivationPath(result);
-        runProgram(settings.nixBinDir + "/nix-shell", true, {state->store->printStorePath(drvPath)});
+        runNix("nix-shell", {state->store->printStorePath(drvPath)});
    }

    else if (command == ":b" || command == ":i" || command == ":s") {
@ -477,7 +497,7 @@ bool NixRepl::processLine(string line)
               but doing it in a child makes it easier to recover from
               problems / SIGINT. */
            try {
-                runProgram(settings.nixBinDir + "/nix", true, {"build", "--no-link", drvPathRaw});
+                runNix("nix", {"build", "--no-link", drvPathRaw});
                auto drv = state->store->readDerivation(drvPath);
                std::cout << std::endl << "this derivation produced the following outputs:" << std::endl;
                for (auto & i : drv.outputsAndOptPaths(*state->store))
@ -485,9 +505,9 @@ bool NixRepl::processLine(string line)
            } catch (ExecError &) {
            }
        } else if (command == ":i") {
-            runProgram(settings.nixBinDir + "/nix-env", true, {"-i", drvPathRaw});
+            runNix("nix-env", {"-i", drvPathRaw});
        } else {
-            runProgram(settings.nixBinDir + "/nix-shell", true, {drvPathRaw});
+            runNix("nix-shell", {drvPathRaw});
        }
    }

--- a/src/resolve-system-dependencies/local.mk
+++ b/src/resolve-system-dependencies/local.mk
@ -1,4 +1,4 @@
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
  programs += resolve-system-dependencies
 endif

--- a/tests/add.sh
+++ b/tests/add.sh
@ -9,7 +9,7 @@ echo $path2
 if test "$path1" != "$path2"; then
    echo "nix-store --add and --add-fixed mismatch"
    exit 1
-fi    
+fi

 path3=$(nix-store --add-fixed sha256 ./dummy)
 echo $path3
--- a/tests/build-remote-content-addressed-floating.sh
+++ b/tests/build-remote-content-addressed-floating.sh
@ -4,4 +4,6 @@ file=build-hook-ca-floating.nix

 sed -i 's/experimental-features .*/& ca-derivations/' "$NIX_CONF_DIR"/nix.conf

+CONTENT_ADDRESSED=true
+
 source build-remote.sh
--- a/tests/build-remote.sh
+++ b/tests/build-remote.sh
@ -6,12 +6,17 @@ unset NIX_STATE_DIR

 function join_by { local d=$1; shift; echo -n "$1"; shift; printf "%s" "${@/#/$d}"; }

+EXTRA_SYSTEM_FEATURES=()
+if [[ -n "$CONTENT_ADDRESSED" ]]; then
+    EXTRA_SYSTEM_FEATURES=("ca-derivations")
+fi
+
 builders=(
  # system-features will automatically be added to the outer URL, but not inner
  # remote-store URL.
-  "ssh://localhost?remote-store=$TEST_ROOT/machine1?system-features=foo - - 1 1 foo"
-  "$TEST_ROOT/machine2 - - 1 1 bar"
-  "ssh-ng://localhost?remote-store=$TEST_ROOT/machine3?system-features=baz - - 1 1 baz"
+  "ssh://localhost?remote-store=$TEST_ROOT/machine1?system-features=$(join_by "%20" foo ${EXTRA_SYSTEM_FEATURES[@]}) - - 1 1 $(join_by "," foo ${EXTRA_SYSTEM_FEATURES[@]})"
+  "$TEST_ROOT/machine2 - - 1 1 $(join_by "," bar ${EXTRA_SYSTEM_FEATURES[@]})"
+  "ssh-ng://localhost?remote-store=$TEST_ROOT/machine3?system-features=$(join_by "%20" baz ${EXTRA_SYSTEM_FEATURES[@]}) - - 1 1 $(join_by "," baz ${EXTRA_SYSTEM_FEATURES[@]})"
 )

 chmod -R +w $TEST_ROOT/machine* || true
--- a/tests/build.sh
+++ b/tests/build.sh
@ -1,7 +1,7 @@
 source common.sh

 expectedJSONRegex='\[\{"drvPath":".*multiple-outputs-a.drv","outputs":\{"first":".*multiple-outputs-a-first","second":".*multiple-outputs-a-second"}},\{"drvPath":".*multiple-outputs-b.drv","outputs":\{"out":".*multiple-outputs-b"}}]'
-nix build -f multiple-outputs.nix --json a.all b.all | jq --exit-status '
+nix build -f multiple-outputs.nix --json a.all b.all --no-link | jq --exit-status '
  (.[0] |
    (.drvPath | match(".*multiple-outputs-a.drv")) and
    (.outputs.first | match(".*multiple-outputs-a-first")) and
@ -10,10 +10,10 @@ nix build -f multiple-outputs.nix --json a.all b.all | jq --exit-status '
    (.drvPath | match(".*multiple-outputs-b.drv")) and
    (.outputs.out | match(".*multiple-outputs-b")))
 '
-
 testNormalization () {
    clearStore
-    outPath=$(nix-build ./simple.nix)
+    outPath=$(nix-build ./simple.nix --no-out-link)
    test "$(stat -c %Y $outPath)" -eq 1
 }
+
 testNormalization
--- a/tests/ca/duplicate-realisation-in-closure.sh
+++ b/tests/ca/duplicate-realisation-in-closure.sh
@ -0,0 +1,26 @@
+source ./common.sh
+
+sed -i 's/experimental-features .*/& ca-derivations ca-references/' "$NIX_CONF_DIR"/nix.conf
+
+export REMOTE_STORE_DIR="$TEST_ROOT/remote_store"
+export REMOTE_STORE="file://$REMOTE_STORE_DIR"
+
+rm -rf $REMOTE_STORE_DIR
+clearStore
+
+# Build dep1 and push that to the binary cache.
+# This entails building (and pushing) current-time.
+nix copy --to "$REMOTE_STORE" -f nondeterministic.nix dep1
+clearStore
+sleep 2 # To make sure that `$(date)` will be different
+# Build dep2.
+# As we’ve cleared the cache, we’ll have to rebuild current-time. And because
+# the current time isn’t the same as before, this will yield a new (different)
+# realisation
+nix build -f nondeterministic.nix dep2 --no-link
+
+# Build something that depends both on dep1 and dep2.
+# If everything goes right, we should rebuild dep2 rather than fetch it from
+# the cache (because that would mean duplicating `current-time` in the closure),
+# and have `dep1 == dep2`.
+nix build --substituters "$REMOTE_STORE" -f nondeterministic.nix toplevel --no-require-sigs --no-link
--- a/tests/ca/gc.sh
+++ b/tests/ca/gc.sh
@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+# Ensure that garbage collection works properly with ca derivations
+
+source common.sh
+
+sed -i 's/experimental-features .*/& ca-derivations ca-references/' "$NIX_CONF_DIR"/nix.conf
+
+export NIX_TESTS_CA_BY_DEFAULT=1
+
+cd ..
+source gc.sh
--- a/tests/ca/nix-shell.sh
+++ b/tests/ca/nix-shell.sh
@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+source common.sh
+
+sed -i 's/experimental-features .*/& ca-derivations ca-references nix-command flakes/' "$NIX_CONF_DIR"/nix.conf
+
+CONTENT_ADDRESSED=true
+cd ..
+source ./nix-shell.sh
+
--- a/tests/ca/nondeterministic.nix
+++ b/tests/ca/nondeterministic.nix
@ -0,0 +1,35 @@
+with import ./config.nix;
+
+let mkCADerivation = args: mkDerivation ({
+    __contentAddressed = true;
+    outputHashMode = "recursive";
+    outputHashAlgo = "sha256";
+} // args);
+in
+
+rec {
+  currentTime = mkCADerivation {
+    name = "current-time";
+    buildCommand = ''
+      mkdir $out
+      echo $(date) > $out/current-time
+    '';
+  };
+  dep = seed: mkCADerivation {
+    name = "dep";
+    inherit seed;
+    buildCommand = ''
+      echo ${currentTime} > $out
+    '';
+  };
+  dep1 = dep 1;
+  dep2 = dep 2;
+  toplevel = mkCADerivation {
+    name = "toplevel";
+    buildCommand = ''
+      test ${dep1} == ${dep2}
+      touch $out
+    '';
+  };
+}
+
--- a/tests/ca/post-hook.sh
+++ b/tests/ca/post-hook.sh
@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+source common.sh
+
+sed -i 's/experimental-features .*/& ca-derivations ca-references nix-command flakes/' "$NIX_CONF_DIR"/nix.conf
+
+export NIX_TESTS_CA_BY_DEFAULT=1
+cd ..
+source ./post-hook.sh
+
+
--- a/tests/ca/recursive.sh
+++ b/tests/ca/recursive.sh
@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+source common.sh
+
+sed -i 's/experimental-features .*/& ca-derivations ca-references nix-command flakes/' "$NIX_CONF_DIR"/nix.conf
+
+export NIX_TESTS_CA_BY_DEFAULT=1
+cd ..
+source ./recursive.sh
+
+
--- a/tests/ca/substitute.sh
+++ b/tests/ca/substitute.sh
@ -17,11 +17,15 @@ buildDrvs () {

 # Populate the remote cache
 clearStore
-buildDrvs --post-build-hook ../push-to-store.sh
+nix copy --to $REMOTE_STORE --file ./content-addressed.nix

 # Restart the build on an empty store, ensuring that we don't build
 clearStore
-buildDrvs --substitute --substituters $REMOTE_STORE --no-require-sigs -j0
+buildDrvs --substitute --substituters $REMOTE_STORE --no-require-sigs -j0 transitivelyDependentCA
+# Check that the thing we’ve just substituted has its realisation stored
+nix realisation info --file ./content-addressed.nix transitivelyDependentCA
+# Check that its dependencies have it too
+nix realisation info --file ./content-addressed.nix dependentCA rootCA

 # Same thing, but
 # 1. With non-ca derivations
--- a/tests/check.nix
+++ b/tests/check.nix
@ -44,7 +44,7 @@ with import ./config.nix;
  };

  hashmismatch = import <nix/fetchurl.nix> {
-    url = "file://" + toString ./dummy;
+    url = "file://" + builtins.getEnv "TMPDIR" + "/dummy";
    sha256 = "0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73";
  };

--- a/tests/check.sh
+++ b/tests/check.sh
@ -74,12 +74,13 @@ nix-build check.nix -A fetchurl --no-out-link --check
 nix-build check.nix -A fetchurl --no-out-link --repair
 [[ $(cat $path) != foo ]]

+echo 'Hello World' > $TMPDIR/dummy
 nix-build check.nix -A hashmismatch --no-out-link || status=$?
 [ "$status" = "102" ]

-echo -n > ./dummy
+echo -n > $TMPDIR/dummy
 nix-build check.nix -A hashmismatch --no-out-link
-echo 'Hello World' > ./dummy
+echo 'Hello World' > $TMPDIR/dummy

 nix-build check.nix -A hashmismatch --no-out-link --check || status=$?
 [ "$status" = "102" ]
--- a/tests/config.nix.in
+++ b/tests/config.nix.in
@ -1,3 +1,12 @@
+let
+  contentAddressedByDefault = builtins.getEnv "NIX_TESTS_CA_BY_DEFAULT" == "1";
+  caArgs = if contentAddressedByDefault then {
+    __contentAddressed = true;
+    outputHashMode = "recursive";
+    outputHashAlgo = "sha256";
+  } else {};
+in
+
 rec {
  shell = "@bash@";

@ -13,6 +22,6 @@ rec {
      builder = shell;
      args = ["-e" args.builder or (builtins.toFile "builder-${args.name}.sh" "if [ -e .attrs.sh ]; then source .attrs.sh; fi; eval \"$buildCommand\"")];
      PATH = path;
-    } // removeAttrs args ["builder" "meta"])
+    } // caArgs // removeAttrs args ["builder" "meta"])
    // { meta = args.meta or {}; };
 }
--- a/tests/dummy
+++ b/tests/dummy
@ -0,0 +1 @@
+Hello World
--- a/tests/fetchGit.sh
+++ b/tests/fetchGit.sh
@ -189,3 +189,7 @@ path8=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$rep
 rev4=$(git -C $repo rev-parse HEAD)
 rev4_nix=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"HEAD\"; }).rev")
 [[ $rev4 = $rev4_nix ]]
+
+# The name argument should be handled
+path9=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"HEAD\"; name = \"foo\"; }).outPath")
+[[ $path9 =~ -foo$ ]]
--- a/tests/fetchMercurial.sh
+++ b/tests/fetchMercurial.sh
@ -94,3 +94,8 @@ hg commit --cwd $repo -m 'Bla3'

 path4=$(nix eval --impure --refresh --raw --expr "(builtins.fetchMercurial file://$repo).outPath")
 [[ $path2 = $path4 ]]
+
+echo paris > $repo/hello
+# Passing a `name` argument should be reflected in the output path
+path5=$(nix eval -vvvvv --impure --refresh --raw --expr "(builtins.fetchMercurial { url = \"file://$repo\"; name = \"foo\"; } ).outPath")
+[[ $path5 =~ -foo$ ]]
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@ -90,76 +90,14 @@ EOF
 git -C $nonFlakeDir add README.md
 git -C $nonFlakeDir commit -m 'Initial'

-cat > $registry <<EOF
-{
-  "version": 2,
-  "flakes": [
-    { "from": {
-        "type": "indirect",
-        "id": "flake1"
-      },
-      "to": {
-        "type": "git",
-        "url": "file://$flake1Dir"
-      }
-    },
-    { "from": {
-        "type": "indirect",
-        "id": "flake2"
-      },
-      "to": {
-        "type": "git",
-        "url": "file://$flake2Dir"
-      }
-    },
-    { "from": {
-        "type": "indirect",
-        "id": "flake3"
-      },
-      "to": {
-        "type": "git",
-        "url": "file://$flake3Dir"
-      }
-    },
-    { "from": {
-        "type": "indirect",
-        "id": "flake4"
-      },
-      "to": {
-        "type": "indirect",
-        "id": "flake3"
-      }
-    },
-    { "from": {
-        "type": "indirect",
-        "id": "flake5"
-      },
-      "to": {
-        "type": "hg",
-        "url": "file://$flake5Dir"
-      }
-    },
-    { "from": {
-        "type": "indirect",
-        "id": "nixpkgs"
-      },
-      "to": {
-        "type": "indirect",
-        "id": "flake1"
-      }
-    },
-    { "from": {
-        "type": "indirect",
-        "id": "templates"
-      },
-      "to": {
-        "type": "git",
-        "url": "file://$templatesDir"
-      }
-    }
-  ]
-}
-EOF
+# Construct a custom registry, additionally test the --registry flag
+nix registry add --registry $registry flake1 git+file://$flake1Dir
+nix registry add --registry $registry flake2 git+file://$flake2Dir
+nix registry add --registry $registry flake3 git+file://$flake3Dir
+nix registry add --registry $registry flake4 flake3
+nix registry add --registry $registry flake5 hg+file://$flake5Dir
+nix registry add --registry $registry nixpkgs flake1
+nix registry add --registry $registry templates git+file://$templatesDir

 # Test 'nix flake list'.
 [[ $(nix registry list | wc -l) == 7 ]]
@ -405,6 +343,8 @@ nix registry add flake1 flake3
 [[ $(nix registry list | wc -l) == 8 ]]
 nix registry pin flake1
 [[ $(nix registry list | wc -l) == 8 ]]
+nix registry pin flake1 flake3
+[[ $(nix registry list | wc -l) == 8 ]]
 nix registry remove flake1
 [[ $(nix registry list | wc -l) == 7 ]]

--- a/tests/gc.sh
+++ b/tests/gc.sh
@ -12,7 +12,7 @@ ln -sf $outPath "$NIX_STATE_DIR"/gcroots/foo
 nix-store --gc --print-roots | grep $outPath
 nix-store --gc --print-live | grep $outPath
 nix-store --gc --print-dead | grep $drvPath
-if nix-store --gc --print-dead | grep $outPath; then false; fi
+if nix-store --gc --print-dead | grep -E $outPath$; then false; fi

 nix-store --gc --print-dead

--- a/tests/init.sh
+++ b/tests/init.sh
@ -35,5 +35,3 @@ nix-store --init

 # Did anything happen?
 test -e "$NIX_STATE_DIR"/db/db.sqlite
-
-echo 'Hello World' > ./dummy
--- a/tests/local.mk
+++ b/tests/local.mk
@ -2,6 +2,7 @@ nix_tests = \
  hash.sh lang.sh add.sh simple.sh dependencies.sh \
  config.sh \
  gc.sh \
+  ca/gc.sh \
  gc-concurrent.sh \
  gc-auto.sh \
  referrers.sh user-envs.sh logging.sh nix-build.sh misc.sh fixed.sh \
@ -38,6 +39,7 @@ nix_tests = \
  search.sh \
  nix-copy-ssh.sh \
  post-hook.sh \
+  ca/post-hook.sh \
  function-trace.sh \
  recursive.sh \
  describe-stores.sh \
@ -46,9 +48,12 @@ nix_tests = \
  compute-levels.sh \
  ca/build.sh \
  ca/build-with-garbage-path.sh \
+  ca/duplicate-realisation-in-closure.sh \
  ca/substitute.sh \
  ca/signatures.sh \
+  ca/nix-shell.sh \
  ca/nix-run.sh \
+  ca/recursive.sh \
  ca/nix-copy.sh
  # parallel.sh

--- a/tests/nix-shell.sh
+++ b/tests/nix-shell.sh
@ -2,6 +2,20 @@ source common.sh

 clearStore

+if [[ -n ${CONTENT_ADDRESSED:-} ]]; then
+    nix-shell () {
+        command nix-shell --arg contentAddressed true "$@"
+    }
+
+    nix_develop() {
+        nix develop --arg contentAddressed true "$@"
+    }
+else
+    nix_develop() {
+        nix develop "$@"
+    }
+fi
+
 # Test nix-shell -A
 export IMPURE_VAR=foo
 export SELECTED_IMPURE_VAR=baz
@ -41,7 +55,7 @@ output=$(NIX_PATH=nixpkgs=shell.nix nix-shell --pure -p foo bar --run 'echo "$(f
 [ "$output" = "foo bar" ]

 # Test nix-shell shebang mode
-sed -e "s|@ENV_PROG@|$(type -p env)|" shell.shebang.sh > $TEST_ROOT/shell.shebang.sh
+sed -e "s|@ENV_PROG@|$(type -P env)|" shell.shebang.sh > $TEST_ROOT/shell.shebang.sh
 chmod a+rx $TEST_ROOT/shell.shebang.sh

 output=$($TEST_ROOT/shell.shebang.sh abc def)
@ -49,7 +63,7 @@ output=$($TEST_ROOT/shell.shebang.sh abc def)

 # Test nix-shell shebang mode again with metacharacters in the filename.
 # First word of filename is chosen to not match any file in the test root.
-sed -e "s|@ENV_PROG@|$(type -p env)|" shell.shebang.sh > $TEST_ROOT/spaced\ \\\'\"shell.shebang.sh
+sed -e "s|@ENV_PROG@|$(type -P env)|" shell.shebang.sh > $TEST_ROOT/spaced\ \\\'\"shell.shebang.sh
 chmod a+rx $TEST_ROOT/spaced\ \\\'\"shell.shebang.sh

 output=$($TEST_ROOT/spaced\ \\\'\"shell.shebang.sh abc def)
@ -58,7 +72,7 @@ output=$($TEST_ROOT/spaced\ \\\'\"shell.shebang.sh abc def)
 # Test nix-shell shebang mode for ruby
 # This uses a fake interpreter that returns the arguments passed
 # This, in turn, verifies the `rc` script is valid and the `load()` script (given using `-e`) is as expected.
-sed -e "s|@SHELL_PROG@|$(type -p nix-shell)|" shell.shebang.rb > $TEST_ROOT/shell.shebang.rb
+sed -e "s|@SHELL_PROG@|$(type -P nix-shell)|" shell.shebang.rb > $TEST_ROOT/shell.shebang.rb
 chmod a+rx $TEST_ROOT/shell.shebang.rb

 output=$($TEST_ROOT/shell.shebang.rb abc ruby)
@ -66,21 +80,27 @@ output=$($TEST_ROOT/shell.shebang.rb abc ruby)

 # Test nix-shell shebang mode for ruby again with metacharacters in the filename.
 # Note: fake interpreter only space-separates args without adding escapes to its output.
-sed -e "s|@SHELL_PROG@|$(type -p nix-shell)|" shell.shebang.rb > $TEST_ROOT/spaced\ \\\'\"shell.shebang.rb
+sed -e "s|@SHELL_PROG@|$(type -P nix-shell)|" shell.shebang.rb > $TEST_ROOT/spaced\ \\\'\"shell.shebang.rb
 chmod a+rx $TEST_ROOT/spaced\ \\\'\"shell.shebang.rb

 output=$($TEST_ROOT/spaced\ \\\'\"shell.shebang.rb abc ruby)
 [ "$output" = '-e load(ARGV.shift) -- '"$TEST_ROOT"'/spaced \'\''"shell.shebang.rb abc ruby' ]

 # Test 'nix develop'.
-nix develop -f shell.nix shellDrv -c bash -c '[[ -n $stdenv ]]'
+nix_develop -f shell.nix shellDrv -c bash -c '[[ -n $stdenv ]]'

 # Ensure `nix develop -c` preserves stdin
 echo foo | nix develop -f shell.nix shellDrv -c cat | grep -q foo

 # Ensure `nix develop -c` actually executes the command if stdout isn't a terminal
-nix develop -f shell.nix shellDrv -c echo foo |& grep -q foo
+nix_develop -f shell.nix shellDrv -c echo foo |& grep -q foo

 # Test 'nix print-dev-env'.
+[[ $(nix print-dev-env -f shell.nix shellDrv --json | jq -r .variables.arr1.value[2]) = '3 4' ]]
+
 source <(nix print-dev-env -f shell.nix shellDrv)
 [[ -n $stdenv ]]
+[[ ${arr1[2]} = "3 4" ]]
+[[ ${arr2[1]} = $'\n' ]]
+[[ ${arr2[2]} = $'x\ny' ]]
+[[ $(fun) = blabla ]]
--- a/Show more
+++ b/Show more
				`@ -0,0 +1 @@`
				`$(eval $(call install-file-as, $(d)/completion.fish, $(datarootdir)/fish/vendor_completions.d/nix.fish, 0644))`